What
is a string? A series of bytes? Characters? What locale is being used? What are you assigning it to? What's dealing with memory? What happens when you leave current scope? What if the two strings aren't the same type, or one or both of them contains "binary" (and what
is binary)? What are you doing with the string? Does your language have a bunch of fancy features like calculating length, taking slices, copying? Are you going to read character by character, or use a regex? Are you going to implement a state machine, linked list, hash, sorting algorithm, objects/classes? For any of the functions you'll be passing this data to, will they ever expect some specific type, much less encoding, specific character set, or length? Do you need to use "safe" functions "safely"? What do you do about 3rd party libraries, external applications, network sockets? Are your operations thread-safe and concurrent?
Higher-level languages, being, you know, higher-level, have a barrage of subtly difficult and uninteresting crap taken care of for you. Sure, you could "write some handy abstractions which will result in better security and dev. experience". And you would end up with.... a high-level language. But it would be slow, fat, and there'd be a dozen things you just couldn't do. Kernels and crypto pretty much need to be low-level.
The real reason low-level languages don't get any easier to program in is standards bodies. A bunch of chuckleheads argue over the dumbest things and it takes two decades to get some marginally better feature built into the language, or some braindeadness removed. There's only so much that function abstractions can do before you lose the low-level benefits of speed, size and control. (and to be fair, good compilers aren't exactly easy to write)