You've got to remember this isn't about completely stripping away the right to strike. It's about taking steps first of all to ensure strikes can be avoided.
It's a bit like the court system if you're litigating. The courts will look unfavourably on any party which chooses not to engage in any form of alternative dispute resolution. Therefore getting the unions around the table to mediate first and then making sure no strike can still go ahead without the specified majority vote is just a means of helping to avoid the unnecessary. Strikes are costly on the economy and a burden to the vast majority of londoners.
It's a bit like the court system if you're litigating. The courts will look unfavourably on any party which chooses not to engage in any form of alternative dispute resolution. Therefore getting the unions around the table to mediate first and then making sure no strike can still go ahead without the specified majority vote is just a means of helping to avoid the unnecessary. Strikes are costly on the economy and a burden to the vast majority of londoners.