So in this case, if his prior contract did not have the objectionable clause, the new employer may not add it.
But then again, employees can also legally expect to receive a decent amount of holiday, and a number of other rights not accorded to those in the US.
And I think the state needs to stand up for employees, because (especially non-unionized) employees in most professions are never going to have the bargaining power to make it a fair relationship.
(I say this as an employer not an employee)
But we have to remember that not every other industry works the same as ours.
Imagine an average mother working at the tills at Walmart. Is she ever going to be good enough at that job that she is going to earn 'bargaining power' by virtue of her merit?
No. Some jobs can be done without a huge amount of training, talent or skill. It is in the company's interest to push down pay and working conditions as much as possible (as the employee is easily replaceable). Therefore it is the state's job to set minimum standards.
Even then there are protections about sacking too many people at once. ie, you can't redefine an entire department's responsibilities and then sack them for not doing their new unrealistic job roles.
Once you meet a certain threshold of layoffs everyone has to go through the redundancy process of getting a pay-out, being offered services to find a new job, etc., etc.
(IANAL, IIRC, etc.)
The employment relationship (in the UK, at any rate) is a contractual arrangement between two parties. One side of that agreement can't opt out of their legal obligations by playing corporate musical chairs.