How would you feel if the US government ran on servers from a European company, which also works very hard to avoid paying taxes in US soil?

All those reasons to go AWS hold for a private company, not for a government service of a first world country and G7 member. AWS has a lot of compliant services, but it's not like they're doing rocket science one of the top 5 richest countries in the world cannot afford to develop or contract within its borders.

The simple reason is that the UK has been on a long trend of selling out to the highest bidder, whether they are US tax avoiding companies, chinese or managed by Russian oligarchs. We have chosen AWS for the same reason Post Office chose Fujitsu.