A pedantic point, buffer overflow protection and the GC are separate things. Buffer overflow protection is bounds checking, GC's are ensuring memory that is no longer in use is reclaimed. But the boundaries on the programs you mention, are more to do with the system not allowing these actions than the language.

Also, there are other ways to achieve memory safety for all but maybe a few cases without a GC. One being ref counted structures that have loops in the links. Another case, but it has work arounds, is postponing the cleanup until a later time. But C++ provides guarantees like, at scope end the destructors(finalizers) are run and the values are cleaned up. This allows for more than memory safety and can include other resources too. This is easier in greenfield projects where old idioms/C compatibility are more common.

To add to your point, high level abstractions allow for optimal code as it is more declarative. The low level constructs to make it fast are of no concern to the caller. And one can build upon this for new higher level abstractions.