In this example from Pennsylvania from Hoo87, I looked up what PA does to purge voter rolls, and it seems like his examples are either a county breaking the law by not following purging requirements or were people with the same names (either of which could very well be true - want to be clear I'm not saying Hoo87 is lying).

Here's one article I found that talks about the 100,000-200,000+ people purged from PA voter rolls every year, including how they track & remove people who moved out of state.

Every time this comes up and I look up the purging rules in another state, I find that they have similar laws and detailed processes for how they track & purge people who moved, died, etc. I'm sure some states are more lax and some more stringent, but what Dems oppose is excessive rules for purging, like removing people who didn't vote in the last 2 elections and no other reason, that Republicans push to make it harder for people to vote.