Adding the same caveat as before that it's a random website with minimal provenance (and one that can't spell GAMSTOP correctly). If someone has a link to a more reputable source that would be appreciated.
I can see BACTA using legacy machines as a "shield" to try and protect against further regulations - because the type of monitoring that would come in is likely to heavily impact some of their client base (the "whales").
If, as previously mused, we're talking about 2007+ machines, then there could be options (such as lowering them to category C or D) but they would argue that it is floor space "wasted" with lower jackpot machines (at 10p per spin rather than 30p/50p/£1).
As lemon mentioned above, the reality is that they'd rather have AWPs at 72-80% which they can buy for cheap, than "FOBTs" at 90%+ they have to rent for extended periods.
The bookies are now quite hot in that from what I've heard they'll only allow you to play one machine so they can keep track of your dosh and their (no disrespect intended here) minimum wage staff are forced to intervene at certain points e.g. £500 in to gather some details from you and ask if you're OK, if the arcades are forced to follow suit they might as well just turn off the lights for good
As you say, the yellow screens are more likely to be activated in error rather than used for their intended purpose.
This is why they wanted the single customer view (SCV) for online sites - a privacy nightmare of data that operators would use
to ban winning players for responsible gambling purposes.
It would have solved the "hoppers" playing across multiple sites, but more likely would have pushed people to the high seas because it'll be a matter of
when they get smacked with paperwork demands rather than
if at that point. The new GAMPROTECT program will probably have a similar outcome as you're banned from one "for SE purposes" and you're banned from all without meaningful appeal.