Well, yes and no.
Quantum computers will likely never beat classical computing on classical algorithms, for exactly the reasons you stated, classical just has too much of a head start.
But there are certain problems with quantum algorithms that are exponentially faster than the classical algorithms. Quantum computers will be better on those problems very quickly, but we are still working on building reliable QCs. Also, we currently don’t know very many quantum algorithms with that degree of speedup, so as others have said there isn’t many use cases for QCs yet.
Senate seats are ALWAYS state-wide elections, with no district lines to draw or gerrymander. Gerrymandering still arguably has an impact on senate elections, but it’s a secondary factor of reducing turnout and not a primary factor of just picking the best districts.