If people don’t pay federal taxes, that should not disenfranchise them. They might be retirees who are invested in muni bonds (for example).
I’ve long thought that the disqualification of taking federal money for voting is a good idea. It harkens back to the Founders’ ideal that only property owners had the vote - and property owners in those days were the taxpayers, since we had no income taxes.
The 24th Amendment put an end to any tax prerequisite to voting.