Mostly there are aren't too many Global items, but in clothing particularly they can crowd out the rest, and seem to intentionally block the exact same item if it's not directly from Amazon UK. It can be quite frustrating, particularly as many are stuff UK used to carry. Though it's not among the main contributors to why I rarely use Amazon much at all any more.
Amazon without the Prime filter is just Ebay with much worse prices and UX.
The most annoying thing however is when the search contains an item, then the description on the item's dedicated page has text that specifically says that the item will ship to my address, but then during checkout I get an error message saying that the specific item can't be shipped after all. Feels like the description page text is determined willy-nilly and it's not until the checkout that they take into account the package size and weight.
However I sometimes do want to see what's available even without direct shipping to me, because if the item is cheap enough or rare enough, it will be worth using a reshipping service in whatever country Amazon does ship to.