This is basically a matter of inertia. The employer will be reluctant to make a change without being sure it’s ok. Being satisfied that a change is ok involves some mental effort, and probably also some consultation. You’ll need to be quite important to your employer before you will be able to get them to engage with the problem at all.

But once you realise how strong a force inertia is, you can put it to work for you. If there’s something in the contract your employer sends you that object to, a tactic that has a better chance of succeeding is simply to amend the bits you don’t like in manuscript, sign it and send it back (keeping a copy). Lots of HR officers will just file and forget at this point – leaving it open to you to argue, if it ever comes to it, that your amended version is the version that was agreed. This won’t solve disagreements about the day-to-day fundamentals of your contract – salary, working hours, holiday etc – but for the kind of content that probably won’t arise and is there ‘just in case,’ it may well do the trick.