I refer you to the earlier post: Good news: ‘Despite this sweeping change across the EU, Great Britain has decided not to implement the regulation.’
But manufacturers aren’t going to bother making GB-specification cars just because GB says they can. We’ll get cars that comply with the EU rules because it’s cheaper and simpler for manufacturers to follow one set of rules. It might be different for other global markets, but in Europe (including GB), there will be only one set of rules that matter to manufacturers – EU rules. Yes, manufacturers make right-hand drive cars for GB and other markets. But that’s because the effort is worth it. Manufacturers have worked out it won’t be worth the effort to make GB-specification cars without speed limiters, even though GB rules say they can.
Your taking country specific software not hardware in this case!
That said, manufacturers sell based on country by country spec rather than one size fits all.