That'll be because public sector wages are abysmal.
Also, at mine we've just had it announced that we are no longer going to be getting sick pay "for the first three days of absence", which effectively means never going off sick, as doing so would cost me nearly £350. Neither me, nor anyone I work with, can afford a hit like that so everyone will be coming to work when they're sick as a dog and spreading it to everyone. Awesome stuff.
They're also taking away the paid 30 minute lunch break (which, err, we'll be ****ing taking anyway because unless they're doing spot checks for sandwiches they're not going to know) and a whole bunch of extra bonus surprises.
And yet it's even worse for anyone starting now; for anyone who started with the company in 2016 or later, they're chopping of a week's holiday and also capping the pay. If I've read it right they're setting the pay for a newly trained MANAGER at £9.50 an hour. £9.50!!

. That's as in, a
full shop manager, not a duty/deputy/customer service manager. I can all but guarantee that quite simply no one is going to want the job for that. We're struggling to keep on cashiers for more than 4 or 5 months on £7.60.
Race to the bottom. I can't wait for my wife to graduate. That's when I finally get to tell them that they can go and suck a dick.