As someone living in a state with mail-in ballots, it still boggles my mind waiting in line for physical voting is a thing. Mail-in ballots seem to be the best of all worlds. It's easy. I have time to do the research for who I want to choose. It's all backed by USPS so it's pretty damn secure- as secure as everything else we trust in the mail.
There are certainly other failure modes. In the last Hungarian parliamentary election the ruling party got less than 50% of the votes overall but literally 99% of the postal vote. That seems rather fishy to me.
Anyway, if you have long lines, that means the people organizing your elections are not doing their job right. There need to be more polling places. Other civilized countries manage this, the US would only need to take their democracy seriously.