Due to the nature of bikes there’s probably a ton of weight saving that’s going on, which is why stuff breaks so easy. With cars they’re so over engineered that they weigh a (few) ton(s) and are generally over built for their expected stress levels.

Because bikes are so small they’re harder to add in that element of over building.

Oh, and the manufacturers are greedy and want the largest profit margin

My e-bike (Onyx RCR, basically a motorcycle) hasn't needed anything of the sort. So it might be either a specific manufacturer thing and/or a cargo bike thing. I can imagine them using regular bike parts even though it's taking way more weight/stress.

For pedal bikes, they can be that reliable if you want to pay for it:

• hub gearbox (a rohloff gets 100,000km minimum)
• decent belt drive (30,000km)
• solid tires get 5,000km. Not as good as car tires but there's a reason; any additional durability will add noticeable drag/weight. Super thick e-bike tires could probably get 70,000km like a car