I'm asking these questions because I honestly don't know the answer.
When you buy goods in the States, you pay local taxes extra to the ticket price. I don't know if there are also national taxes like we have with V.A.T. Are these taxes reclaimable by US businesses like in our V.A.T. system? Are they chargeable for exported products?
There could be a whole raft of charges made stateside that we may not have knowledge of. It may change the dynamics of comparing like for like. It would be fairer to our UK suppliers too if this could be clarified. Doesn't change the situation though that there are considerable savings to be made for UK individuals.
Another aspect is that, as a rule of thumb, what costs £1 here costs $1 there. So when we get into exchange rates, although UK goods are more expensive, we typically earn more. At present, we have an exchange rate that favours us buying US goods. That could easily change. Just enjoy the benefits whilst they are there.
Safe and happy cleaning

Ken