I just asked around (~100 people) and nobody I know has unlimited mobile data here in the UK. As you can get 120gb/month for £20 and unlimited for £40 on a 12 month sim only contract, I think not many people using more than 120GB/month so no good reason to pay double for it.

As anecdata, I cut my package back to 5GB at the start of the first lockdown as my mobil data usage went to nearly 0 since wifi at home and did not run out of data during the last year. I assume anybody who was able to do that done the same.