The vast majority of states offer a multitude of early voting or absentee/mail in voting options. As far as uniform regulations between counties, who cares? Each person is only supposed to vote once, and in a single county. Learn your local regulations (easy as this is well documented) and follow them.

Further, you won't ever come up with a system that is 100% inclusive, secure, reliable, and economical. That should never be the goal since it's not achievable or necessary. Covering 99% of cases is good enough.