Many do, but only use it when convenient. For instance, Fitbit used "no recipt => potential fake" to flake on the warranty for my $300 watch. They absolutely d

Many do, but only use it when convenient. For instance, Fitbit used "no recipt => potential fake" to flake on the warranty for my $300 watch. They absolutely do keep and track serial numbers because actual fakes get detected and kicked out of the fitbit app, but the fact that this database isn't public still lets them use fakes as scapegoats when convenient. Best of both worlds!