Well, believe it or not, even in a country with lax standards like the U.S. there are still ways to get into trouble for misleading advertisements. Look no further than....airlines. They got worse and worse about inventing their own fees (like Spirit's bogus "passenger usage fee" and even trying to make them look like taxes that the actual final price bore no resemblance to the price advertised in big letters. So the DOT, following the lead in other countries, required all-in pricing (of mandatory fees) early on in the Obama administration. The airlines don't like it and will try to get a friendlier administration to undo it against the wishes of customers, but it shows that concepts like transparency and accuracy do matter.

The travel industry in general has a long history of questionable practices generally trying to make something appear cheaper or more beneficial than it actually is, everything from PPDO hotel pricing to car-rent prices advertised in large type with zero included miles to the very business model of some all-inclusives, where the economic incentives are to promise everything and then try to deliver as little as possible (e.g. an open bar but only one per 300 guests, ensuring long lines).

I realize there are caveat-emptor purists who think basically anything should be allowed as long as it's a business doing it (individuals are held to higher standards!), but that's an extreme minority. It's also bad for business because it destroys confidence and makes people so cynical they decide the safest thing to do is stay home or go see relatives by car. If you reward the bad actors then competition results in a race to the bottom, as we've seen in areas like the proliferation of bogus "resort fees" in Las Vegas, even at 1-star hotels. You could do a whole masters thesis on questionable practices just in the travel industry alone and why they keep happening.

I don't expect the situation with the "miles" term to change overnight, but yes, language DOES matter (a lot), and if airlines were proactive they'd see the coming problem with this one. OTOH, assuming proactivity can be as foolhardy as assuming total honesty in marketing, so if I had to bet money I'd say the change would come late and under duress, i.e. only after the general public figures out that a mile flown is no longer a mile earned. People here are only the most-informed tip of the iceberg, and no one is really advertising the changes (unless CapitalOne or someone with a vested interest starts doing so), so awareness will build slowly.