For a lot of things that "they don't make like they used to," a few companies still do make things that way, but everyone else has gone with way cheaper methods and materials. You get used to this lower price, and grumble about lower quality.

People in the past used to have way less stuff, because it was all more expensive. For example: old houses don't have closets because you could fit all your clothes in a single dresser. When you're forced to buy/make expensive stuff, it had better damn well last.

Planned obsolescence is definitely a thing, but it's not always the sole reason cheap stuff sucks.

Expensive clothes are also lower quality / lastability. You can buy the same brand even same size pair of jeans or bra and they are totally different from even a few years ago.