For me it is the concept of registering to vote. I am citizen so I have the right to vote automatically and only thing I need to provide is some accepted ID.
It may make sense for specific services which are naturally bias and unfair (can’t think of any that would warrant it), but for general governance weighting citizens votes differently for any reason is entirely anti-democratic.
Also the UK’s House of Lords is no better. Giving a bunch of historically elite landowners authority based on wealth and birthright is fucking disgusting.