The reason they changed the machines and require the recording of the vehicle reg on the ticket is that they are non-transferable. People were buying tickets, spending a few minutes shopping, and then passing the ticket onto someone else. They were losing quite a bit of income from it.
There are ANPR cameras on site and there is a grace period before a Penalty Charge is imposed but I’m not sure how long that period is at the moment. But until now, there hasn’t been a charge for driving onto the site, dropping or collecting someone, and driving off.