Child labor was legal until 1930. It has been a part of society for longer than it hasn't. I think your calculus is a little off.
> your lifestyle would not exist
Because /some/ children struggle to eat enough? Which, again, has been a norm in our society for longer than it hasn't. We didn't fully get rid of horses as beasts of burden in agriculture until the 1950s.
> you personally don't need to walk places.
Carrying everyone who can't walk is not a universal good. Particularly when some of those people can't walk because of a tiny, temporary, and highly solvable problem.
Now you have people who make it their career to carry people. Their motivations are to carry as many people as is possible. If we actually made it so no one had to be carried they would be out a job.
We live in a world of odd incentives. There is no point at which abandoning the middle way will benefit you, regardless of how pretty those ideas sound.