Many developers have no concept of efficient use of hardware resources (or what hardware resources even are), figuring they can just ask for more of whatever they need and the system will take care of the rest. When your program and anything else including the operating system needs to play nicely in KB or MB of RAM, you're much more careful. Why not be just as careful when you have GB of RAM?

Extensive use of bloated multi-dependancy-level libraries and frameworks when you could just write the code to do what you want to do in 1/100th of the time and space. Copy-paste coders who copy far more code than they actually need.

A lot of developers who grew up coding last century understand, and some later people, but an awful lot of development today is done by people who have no idea what is actually happening when they "read a file". And think that toast requires avocados. (sorry, that was mean). I know some young people who get it, many more who probably should be pursuing a psychology degree. (oops)

Sure, you could argue that the real coders have already done the hard work, and that's why you can just click a few buttons and end up with a working "program". But it really helps to actually understand what's happening under the hood.

Disclaimer: I was apparently so technology-poor that I wrote several quite useful programs in Apple II machine language while in college. Though I had no mouse, it was a far more pleasant experience than working without video, or persistent storage other than punched paper tape, on my high school's PDP-11.