Once again, I judge by deeds not words.
I will bet that byzantine planning laws, and a disjointed approach to infrastructure, plus bunfights over who gets what means that rather than the owners of large retail parks snapping these up, there is a collective disinterest in the scheme.
Even at 50% overall efficiency, and if only 10% of retail parking spaces were used, the UK could have 2GW of "free" electricity. That's 2GW less you need from oil or gas or via Putin or Hormuz.