My biggest barrier to buying from anywhere online is the "you must register" just to find out the shipping costs. At that point, unless there are no alternate suppliers it's a case of sale lost. You do not need me to register or my full personal details just to calculate shipping costs, especially when shipping from UK to UK
In terms of buying from Europe when the price is right I do. Usually tech/electronic items although I still haven't worked out how the prices can differ so much. I bought 2 mobiles from Amazon de which saved £50 each including delivery and both ended up shipping from the UK distribution centre the same day, but was euro stock with euro power plugs inside.
I found the Netherlands usually much more expensive overall on most items, which is a shame because they seem to stock good, but not mainstream media streamers like they're candy.
France often has cheaper lego than Germany and the UK and the last items I bought for my son for his railway were both simple to find and cheaper from Germany, which isn't surprising as they were made by a Germany company.
As for payment, euro, dollar and global currency cards resolve any gouging on currency exchange.
The only items I've had trouble buying outside the UK have always been a result of manufacturer restrictions on supply outside the country of sale or the market place seller on Amazon not offering the required destination. With fulfilled by Amazon the destinations are grouped into tiers and they didn't ship enough to the higher priced tiers to make it worth their while paying Amazon to ship to those countries.
The most surprising purchase I had through Amazon was buying from Amazon UK and still getting free delivery to the Netherlands and it turning up in a few days.
As for her comments about broadcaster and media rights providers.... well Sky make it obvious why.... it's plain and simple price gouging which goes all the way up the chain to the media rights holders. Sky operate in multiple European countries and charge different rates for packages. After Sky lost in court with the cross border sales, Sky UK were already in the process of fixing it by moving to a satellite with directional spot beams only covering the UK to prevent non-uk based subscribers from catching the signals they previously broadcast in a footprint covering a huge chunk of western Europe. There needed to be a new satellite to increase capacity, but by choosing to switch to directional spot beams (which I expect cost more) than the wider fixed footprint transmitters they fixed their cross-border sales issue by making it impossible to receive the signal.
Somehow I can't see her chasing the broadcasters and media companies and ultimately they have alternative ways to prevent cross-border sales, both globally and in Europe. The risk of losing so much money will mean they will find a way to keep that in place.