This is a good point actually. But I think (for now) everyone running a paid relay has outed themselves as the operator. So if they rugged everyone, they would be ostracized by the community or, more fittingly Nostracized
Discussion
Yes I know that reputable players will not do such idiocy for some sats. But be aware, the shitcoiners love to scam, they have into their bloood. And if they would have an opportunity to scam, will do it 100%.