

The short answer is that it depends. Some countries have treaties where civil court judgements (ie money compensation) from overseas are honored domestically, meaning the domestic court would not have to relitigate the facts but would just be to re-issue the local equivalent of an order to pay up.
Seeing as this is a lawsuit in the UK, Valve does not appear to have a dedicated business location in the UK or EU, and that Valve has not already stopped offering services, I would guess that they don’t intend to skip town. The appeals process in British courts is similar to how it is in the USA, so there would be room for any award to be adjusted downward, before being forced to pay it.
Also, to not pay a lawful judgement in one jurisdiction would cause potential issues in other jurisdictions, such as the massive EU market next door. This is precisely because Valve doesn’t operate a subsidiary but is doing business under their USA corporation. So the EU authorities would be within their rights to curtail the same corporation that skipped on a lawsuit in the UK, even when the UK isn’t part of the EU anymore.
Note: some lawsuit judgements are explicitly disallowed from being “repatriated”, such as lawsuits regarding free speech in the USA. Under the SPEECH Act, an overseas judgement for speech that would have been legal if said in the USA. Thus, that judgement cannot be collected on USA territory or against USA bank accounts. It would have to be collected against the person when they’re traveling, or from their non-USA bank accounts.

Even when something is fairly inexpensive and readily available, the nature of the thing may preclude it from being well-noticed in public, even if it’s not being intentionally obscured at all. Things that move are an especially good example, because most people don’t really pay significant attention to passing traffic or stuff moving approximately 3-5x faster than their own walking pace, with the exceptions of when they themselves are in motion too (eg seeing another train while riding a train), or if the object is coming straight at them.
An example suited for fellow Americans: seeing the same color and model of your car, parked in public, is very easy to spot, because that’s how you’re accustomed to seeing your own car: stationary. Whereas seeing your own car in motion (while you’re stationary) is slightly harder because: 1) it’s whizzing by for only a few seconds, and 2) you’re not used to seeing your own car drive away from you. Confirmation bias then means that you rarely see that same model of car in motion.
Drones have the same perceptional bias, but compounded by the fact that humans aren’t in the habit of scanning the skies overhead for drones. And even if they do, identifying a hovering drone means to spot a small dot that’s hanging dozens of meters in the air, or being within earshot (inverse-square law limits this distance). And if the drone is moving, then spotting it is even more difficult, although it does have a moving audible footprint now.
Finally, there’s the operator, which in almost all circumstances is stationary. Yet, for similar reasons, why should anyone notice if someone is standing in a forest, looking at a screen with a set of controls? If nobody is around, is a drone operator even there? As a fairly solitary activity, it’s no surprise that few have ever seen a drone actually being operated, much the same that loads of people know of Pokemon cards and yet few have actually seen the TCG played out on a tabletop (this fediverse audience excepted).
TL;DR: the general public only perceives things that are easily perceivable. When did you last see your car moving?