1. This isn't true whatsoever. You can easily do better than std::vector (trivial relocation support, non-inlined grow), better than C# List<T> (ref T accessor, batch add API, maybe even an add-uninitialised API or in-place constructing specific things), better than a Python list (this one is obvious), etc.

2. This is a better point but depending on your workload, I don't think this is unheard of. Or at the very least, if your workload is simple, you can grab one off the top of the benchmarks, point AI at it to customise it a bit then you're good. But to be fair this one's a bigger structural investment so I do see your point. For smaller utilities the tradeoff is pretty clear.