and in a previous post ...
That would have immediately raised alarm bells for me... not that I'd be ungrateful for them fitting the part for free. However, I presume that they had a mechanic do the work and either the procedure was so secret that they only wanted the 'inner circle' to know how it was done, or the procedure they used violated some written or unwritten law (e.g. 'elf 'n safety'). As someone who occasionally had to 'bend the rules' (I had been known to say to my boss, "Sir, I'm not going to say that I'm about to do something dodgy, but you probably don't want to be in the [name of appropriate machinery space] for the next hour or two!") I know that expediency has its place -- particularly when there's no realistic alternative!
That said, there have been automotive repair procedures that require special tools for many, many decades. However, the specification of those tools was usually general knowledge and the vehicle manufacturer were not the only source of supply. So those tools were typically available from third party suppliers or you could often make them up yourself (or jury rig). Current shenanigans are a different kettle of fish. OBD2 was introduced as a legal requirement under US legislation and was meant to standardise data access across all vehicles -- both emissions testing and 'right to repair' were involved. But just like BMW made life difficult with their special screws, manufacturers are now using proprietary software to lock owners and independents out of maintaining their own vehicles. Worse, they're even fitting features and disabling them unless you give them more money in the form of a subscription. The car has all the hardware needed to fulfil that feature and, since it's actually embodied in the vehicle, you've paid for that hardware. But the manufacturer owns the right to turn it on or off -- so you don't truly own your own vehicle any more, no matter how much you paid for it!