Ask Lemmygrad

Petty bourgeoisie ≠ bourgeoisie. They are best not understood as just the bourgeoisie but slightly smaller, but better understood as essentially a distinct class. The petty bourgeoisie do not necessarily always have class interests aligned with the bourgeoisie. The Manifesto talks about how the petty bourgeoisie may even side with the proletariat at times. It depends upon whether or not they see their future prospects under the capitalist society favorable such that they may grow to become a member of the bourgeoisie, or whether or not they see it as more likely the bourgeoisie will ruin them and they will be hurled into the proletariat. In the latter case, they may find themselves more sympathetic to the proletariat, wanting a social safety net for the workers in anticipation that they may join them soon.

The property relations are also not the same between petty bourgeoisie and bourgeoisie. The petty bourgeoisie are either self-employed, meaning their own their own means of production directly, or they run a fairly small business, so there may technically be antagonisms between the socialization of labor and private appropriation, but the antagonisms are very small. There is a reason you sometimes you hear common people talk positively about "mom and pop shops," because typically with smaller enterprises there is a less of a disconnect between the ownership and the workers so conditions tend to be a bit better than working for a giant faceless megacorporation owned by shareholders who never even stepped foot in the corporation in their lives.

The small scale of petty bourgeoisie property also makes it incapable of being a basis for a socialist society, since a socialist society introduces socialized appropriation on a national scale, so the enterprise must be on a national scale or else the socialist government would be introducing a contradiction between socialized appropriation and private production rather than resolving one. Economic systems aren't moral ideas written on paper, but real physical machines in the real world, that require real infrastructure and computational technologies to run it, and this will limit the scale in which you can meaningfully operate an enterprise.

If a sector of the economy is dominated by the petty bourgeoisie, it means the technology and infrastructure simply has not advanced enough in that sector to nationalize it. If you nationalize it, you will not physically be capable of operating it on a national scale, which will lead to huge bureaucratic problems if you try to do so anyways. The failure of the government to then plan that sector will cause the spontaneous rise in a black market to resolve the government's failures, and if you try to then crush that black market by force, you will just be destroying something that came into existence due to your own government's failures, and thus destroying your own economy.

Small-scale production is simply not the basis for socialist society, and outlawing small-scale production makes zero sense from a Marxian socioeconomic analysis. The proletariat thus can only meaningfully expropriate the property of the bourgeoisie, and then has to focus on encouraging the development of the forces of production, because in the long-run, that will cause much of the petty bourgeoisie to destroy themselves, and the rest to become into the bourgeoisie, which then allows for the gradual extension of that expropriation.

Yes, free lancers and struggling artists are also members of the petty bourgeoisie. That is not an insult because these labels aren't moral judgements, and it's not even a declaration that these people are the "enemy," as, again, the Manifesto points out that the petty bourgeoisie can side with the working class. A self-employed struggling artist might still support working class movements precisely because they are struggling, believing they will likely end up having to get a job in the long-run so they might as well support the proletariat class, and many do. But they also might not, as some might see themselves as just a misunderstood great artist who will one day catch a break and their art will take off, and they will become rich and famous, and because of that belief they could also see their interests as aligned with the bourgeoisie.

The point is just that petty bourgeoisie (1) have their own class interests which are not necessarily aligned with bourgeoisie or proletariat and can side with both depending upon the historical conditions, (2) has a different property form of private production which is too underdeveloped to be the material basis of socialist society as it is distinct from the socialized production of the bourgeoisie, and (3) therefore do not have the same relations to production as either the bourgeoisie or the proletariat.

It is quite common in capitalist societies for the interests of the petty bourgeoisie and bourgeoisie to clash. There are not literally the same class as the bourgeoisie that just happens to be smaller. They are more of a distinct social class. This social class also has a different trajectory to it. The proportion of petty bourgeoisie and bourgeoisie in capitalist society is always shrinking in proportion to proletariat with the development of the forces of production. But when the petty bourgeoisie's numbers shrink, it is because they are destroyed by the bourgeoisie, and so in the long-run, all the petty bourgeoisie are doomed to destruction by the bourgeoisie, but the bourgeoisie cannot destroy themselves, at least not entirely. Only the proletariat can end the bourgeoisie as a class. The trajectories of the two classes are thus also different.