Qt is very reasonable and the standard library also isn't too bad. Boost (some of its sub-projects) is by far the worst in making simple things complicated.
I didn't expect anyone to compliment Qt containers. Most of them are straight up not recommended for any situation because they waste memory, have unnecessary indirections that cause dcache misses, and aren't optimal for multithreading due to COW (and accidental COW due to bad APIs).
This was about ease of use and simplicity of implementation. By the way, QHash's performance will be fixed thoroughly in Qt6. It is significantly faster than std::unordered_map, whose performance is constrained by an API that effectively requires a sub-optimal implementation.