Honestly I chalk this one up mostly to just international trade mercantilism.
The EU relatively weaker at developing international software, so slapping "antitrust fines" on Microsoft (which probably have nonzero merit) is a good way of "group negotiation" to get a bulk discount on Microsoft (US) products.
The analogy is how the USA is relatively less good at making quality cheese and wine compared to the EU, so the USA allows any sparking wine to be labeled "Champagne" and any Emmental-style cheese to be labeled "Swiss".
Trump got many things wrong, but got the trade negotiation right when he slapped back luxury wine tariffs on France in return for France fining US software companies -- bulk discounts in both cases.