They are, and always have been. But what we're discussing here is consumers and b2b customers being forced to deal with companies and shops that will only display and use imperial. This would be absolutely idiotic. As you say, the market would correct, through inefficiency and wastage, companies operating on fine margins would go bust. And for what? So a few little Englander greengrocers can have one more "up yours Delors" moment? Anyone who thinks this is good thing should perhaps think about what they would say to the people and families of these business owners and employees (and to the wider population as a whole who would suffer as an aggregate) who through no fault of their own would feel the economic downside.
Considering your antagonism to companies being forced to only use metric (which isn't even a real phenomenon), don't you think it's inconsistent to then champion some businesses and consumers being forced to only use imperial, when dealing with firms that would choose to do so?
No, they weren't. No laws were ever passed in the UK to display imperial measurements and the older directive that you cite predated the UK's accession to the EC. It was replaced with the later directive, but the UK had already begun metrification anyway and the directive was considered to be in line with the UKs own legal path in this regard. Furthermore the UK government ratified it, but then never passed it, at any point, into UK law. It was not a "sneaky law" that only came to light decades later. It was an EU directive, which never came into effect and was subsequently dropped.
At last you're starting to talk some sense on the matter. However, this POV is totally at odds with what you posted earlier.