They'll still put it in for the jurisdictions that it's valid, or maybe just as a chilling effect. I've signed an employment contract before which contained clauses that were invalid under the law (non-compete and also forced repayment of mandatory training when you leave too soon after), and when the employer was asked whether they knew they were invalid, they admitted they did. Those clauses were only enforceable to people who didn't know any better, and apparently that was sufficient reason to have them in there.
Yes, this is an all-too-common tactic with legalese. I assume that's why in some places even including certain provisions in a consumer contract or failing to advertise certain information about consumer rights is in itself against the law now.
