Negotiate for the removal of these clauses from your contract and don't sign it if they won't remove them. Sometimes this may mean passing on a job but if everyone did this then employers wouldn't try to get away with it.
I don't doubt that future contracts will say "We reserve the right to update this in the future as conditions change in order to remain compliant with applicable regulations and laws and in order to protect the interests of the company."
Once you sign that, even with a permissive clause, they come back later than blam! Change it and you've pre-agreed to their changes which can now be much more restrictive.
The problem is that the effectiveness of this relies on the bargaining power of the employees, which, in a "buyer's market" is not that much.
Better to get the law to change to forbid such abuses for everyone.
Employers looking for developers: 11 Developers looking for work: 2
Austin, TX, for reference.