My experience from the other side of the fence is that this is pretty standard, i.e. nobody would really bother with changing the standard contract for one potential employee unless they were perceived as a crucial asset. The people who do the hiring, the ones who make the decisions and the ones who will work with you later - these are very different groups of people, with some (very temporary) overlap. The hiring ones, just like most people, prefer to avoid unnecessary problems and additional paperwork, and move on.

Mind you, if many people have the same attitude as you, the hiring people may actually make the change happen forcing the people in charge to approve a variant of the contract without that clause and offer it to the ones who complain but are otherwise excellent candidates. But this is not a quick and easy process.