If somebody had stolen the No Parking sign then there's not a presumption that you should have known.
But you cannot say that it was an honest personal mistake. Your state of mind doesn't enter into it.
In some voting right act enforcement it gets down to, "Look... for whatever reason, the numbers show that black people happen not to be voting in these elections at anywhere near the rate black people vote everywhere else, and we will take steps to increase black participation."
I do not see much hope for limiting voter-disenfranchisement if we have to prove what people were thinking when they happened to dump a disproportionate number of Spanish sounding surnamed voters. It really shouldn't matter why.
Take steps to make sure it doesn't happen.
As to whether people mind paying fines, most American voters support voting. I am sure there are mad billionaires who might want to kick in some money to cover the risks of dumping voters but they couldn't. The state would have to pay.
And most citizens (not all, but a strong majority) generally favor voting so the first time their state pays out a few million to needlessly un-rolled voters folks won't like it.
That was not true of some deep south states back in the day. Some states paid an incredible price just to be dicks. For instance, a lot of southern cities (before air conditioning was as universal) closed ALL of their swimming pools when ordered to integrate them. No pools, nothing to integrate.
But I do not see a lot of tax-payers supporting expensive disenfranchisement these days. I dunno... maybe Arizona would pony up the fines to keep trying to dump hispanic voters. But even if so, has it made anything worse? They are already doing it for free.