Memes

However, why would Trump threaten to invade Canada and Greenland if the EU, Canada, Australia, and New Zealand has no autonomy of its own? They certainly wouldn't be turning to China in response to all the tariffs and invasion threats if that was the case.

Personal benefit. Greenland, Denmark and other vassals are not sovereign they are suzerainties. They are allowed limited domestic autonomy( in the case of Greenland specifically the US even got away with dropping a nuke on them with no repercussions)

Despite this Trump could still benefit personally, financially and otherwise from a more direct form of control and knowing his ego I wouldn't be surprised if he just wants to paint Greenland in US colours on the world map so that part of his 'legacy' is increasing the size of the US.

This can be applied to other vassal nations, which cannot be said to be truly 'turning to China' until they take concrete steps to move outside of the US's sphere of influence such as de-dollarizing their economies and switching to RMB as their reserve currency, kicking out US troops from their borders and leaving any military coalitions led by the US occupying foreign nations they are in. Its extremely reductive to separate 'militaristic' issues from wider political ones, especially in this context. Ultimately Trump is a figurehead for the ruling class who's individual control over the empire has limits, his motivations and that of the empire as a whole while usually aligning are not always one and the same