You seem to imply that it doesn’t have any cost. It does. You have to make decisions and, in the case of C++: sometimes you have to deal with a lot of really ugly code to make it “automatic”. And if you really have to count bytes and carefully manage stack sizes because you are writing code for a constrained device, you have to pay even more attention than you would in C.

GC’ed languages have memory related challenges too. But it simply isn’t true that these are on the same order of difficulty as the difficulties that do arise in C++.