But for more regular Joe's, maybe senior engineers or whatever, the previous employer isn't too likely to incur any costs trying to find out who the next employ

But for more regular Joe's, maybe senior engineers or whatever, the previous employer isn't too likely to incur any costs trying to find out who the next employer was? And I'm not too sure if there's a way for a private company to find out who somebody's employer is. I left a really crappy employer about two months into a three month notice period as it was just pointless drudgery. I just kept a low profile on LinkedIn for a year or so afterwards. Didn't think they would have any way of finding out I joined another company straight away.