> UB is simply the latest stick to hit C with. In day-to-day working nobody worries about UB at all as you generally don't notice it.
I agree that in day-to-day working nobody worries about it, and I see odd behaviors all the time because of it. In particular as fewer applications are using C, a much higher fraction of C becomes systems and embedded where you are more likely to accidentally run afoul of choices that were made to compete with FORTRAN on numerical performance.
A read from NULL will crash on most unixen, but will not crash on some targets without an MPU and when running in kernel mode, so may be left lurking (see the linux kernel).
The C89 aliasing rules in particular are completely at odds with a lot of kernel and device driver code, and in addition where the int size was 2 bytes previously but is now 4 bytes you can have signed overflow where before the behavior was well defined:
UINT2 x; // 16 bit integer
...
x+=2; // addition mod 2**16 on 16 bit targets, undefined behavior on 32 bit targets.
These are some real-world bugs I've dealt with.
> (and yes, I do have plenty of experience in it, I've been using it for the past 20 years, have you?).
I've been using it professionally for only about 15 years, but I started using C at home in '92.
[edit]
> Same with lack of a GC; this is a plus point for C for most applications, not a negative.
This is a bit of a non-sequitur, as I didn't mention memory management at all. C doesn't need a GC. It could use more memory safety though. There's been plenty of academic research on improving C's memory safety without significant runtime overhead; a lot of those techniques were used in rust. There are plenty of tools that can catch a large fraction of memory errors at compile time, which is a good thing.