But nowadays it is often seemingly done without proper evidence in some places,
is sometimes applied to cases that do not meet the criteria for it
and in some places it is used for the poor but not for the rich and influential (this occurred with the Jews before too) or it is used for resident workers but not usually for citizens (as in some Gulf states) etc.
people have to be pretty blatant in their zina to allow four witnesses to spot it. From this a lot of learned people are telling us that Rajm is primarily a deterrent.