Not at all.
I've looked at your links and I'm not at all convinced.
Imagine I'm a budding U.K. criminal and I want an AR-15. That Ghost Gunner 2 CNC mill is $1675, it weighs about 23kg so that's going to cost at least several hundred more to ship from the US*. I also need the 80% blank it's designed to machine, another $75. So that's already about twice the Walmart price. Let's assume that I have no problems actually setting it up and milling my part correctly. I now have a AR-15 lower receiver. Yay. So where am I going get the upper receiver, the stock, the trigger, the magazine and all the other parts from? These parts can't just be bought in the U.K. like they can in the US. I can't make them on my shiny new mill, it's not designed for it and there aren't any programs. The only option would be the black market for which I'd need connections and a lot more money...
You think that this is 'not at all' more difficult than just driving to Walmart? Seriously?
*This is assuming that you can even get the company that make it to ship it to Europe and you can get it through both US and U.K. customs, which I think is unlikely.