If Festool (Germany), allows retailers in EU to sell to the USA, it means Festool USA is competing against Festool. Festool USA is its own company (LLC), and has to justify itself, and protect its dealers. If everyone bought stuff from out of the USA, then it just undercuts Festool USA's existence.
It sucks, but it's common thing anytime a company sets up a US company verses just having a distributor. You could compare to Mafell, there is no such thing as Mafell USA. They just have a single distributor in the US. Mafell doesn't do anything to stop people from buying their stuff out of Europe (not that I have noticed anyway). But Timberwolf Tools won't honor a warranty or support you if you bypass them. For Mafell, a sale is a sale in their case. But once you have a full blown operation set up in a country, you don't want to go undercutting that.
Obviously someone could point out that if someone buys something Festool USA sells, but buys it from a different country, that person is hurting themselves by loosing warranty and support, thus will keep things in check. I doubt they see it that way. If Festool opened things up where items not sold by Festool USA were valid for people to buy from out of country, I think that would bring things in better balance. Someone wants a tool that Festool USA has decided won't sell enough of to justify carrying it, let folks buy it. Someone wants a tool that isn't offered such as a 230V tool, let folks buy it. They could potentially set up a separate limited warranty program, where you might even be able to get service of it, or parts from Festool USA, but there may be an additional cost, or time due to parts lead time, or even the tool might have to go back to Europe worst case.
I think most people would be generally understanding of such setups as long as there is no real reason to go those routes (everything is offered in your country). It's Festool not offering all the tools, or making random moves (removal of metric) and so forth that frustrates people and causes them to look to buying them from the EU/UK. I think Festool UK is its own PLC too, but there, I would guess people buy stuff cross channel and no one blinks because that is just a mass flow of goods and just a normal flow of things that trying to stop it just wouldn't work.