When we write code we sit atop a tower of abstractions. You're trusting your language's stdlib, its compilers, the syscalls offered by your kernel, the virtual memory implementation of the kernel. Your coworkers wrote code that you only interact with as a library or over an API of some sort. Let's not even think about the lossy abstraction of taking the ultimate bytecode generated and actually mapping it to the actual CPU pipeline that's running the code.

Modern computing is an exercise in trusting abstractions and then zooming into the abstractions and figuring out what went wrong when something breaks. Just because I wrote a web route doesn't mean I've audited the code behind the web framework, the event loop, the HTTP implementation, the TCP implementation and so forth. By your argument then I've already stopped thinking about my software and can't tell you if it's okay or not.

I'm sympathetic to both the perspective of sadness from the loss of hand coding and the perspective of joy from working at a higher level of abstraction, despite its costs in understanding. It actually seems very simple to me to hold both perspectives within me.