You're using moralizing language, but what else do you think could happen here? Barring government funding, by-the-book remediation costs a lot of money. So the two options are either completely remediating the lead and offer that as a selling point, or just kicking the can down the road ("I don't know but it was painted before 1978 so make your own informed guess"). If the seller checked the box for positive existence of lead, they would be doing you no favors since you'd be getting the exact same physical house, but would also have to check the known-lead box when selling the house down the line.
If you only want to buy a house that has been fully remediated, you could make your offer contingent upon that. But since your offer has to be competitive with the rest of the market, that would cost a similar amount to buying the house as it is and then doing your own remediation afterwards.
If you go to rent that house out and the renters have small kids, then you can no longer kick the can down the road. It makes for a painful immediate situation, but barring government funded remediation or straight up mandating that every bit of lead paint needs to be remediated before a house can be sold (despite it being fine for the majority of people), I don't see how else it could be handled.