There is a "tech agreement" coming which will augment the agreement announced yesterday. Essentially, they announced an agreement before agreeing everything! Probably Trump needed it to get some positive news after his recent nonsense.
Personally, I don't mind the tax being dropped as long as the UK gets something in return that's worth the equivalent or more. We (the UK) export more services to the US than we get in return, so it would seem preferable to make services trade as friction-less as possible.