You see claims like this all the time but they are so blatantly ahistorical its fascinating.
No one but white men could vote in the U.S. until the early 1900s when women were given the right to vote.
And pretty much only white people were allowed to vote until 1965 when black people, Asians, etc were given the right to vote.
The U.S. may call itself the oldest democracy but there are only a handful of democracies that so heavily disenfranchised such significant parts of their population as recently as the US did.
It’s been a little more than 50 years where millions of people were not legally disenfranchised, so by any measure the US population has become more enfranchised.
Further, as the chart in the Wikipedia page below show, voter turnout has been constantly increasing in the US (at least for Presidential elections)
https://en.m.wikipedia.org/wiki/Voter_turnout_in_United_Stat...
The evidence indicates that the populace is becoming less, not more apathetic.