There's no ban on them in Europe
In Europe the market ultimately did decide on the front loader way back in the 1960s and 1970s.
Top loader agitator washing machines, for a whole variety of marketing reasons, didn't take off here. The main reason was that because of WWII, the European economy was pretty much wrecked in the 1940s and 1950s and by the time the consumer spending had recovered in the early 1960s, the front loader automatic had become a practical design. In the US, the top loader agitator machine was the first automatic to be mass-marketed in the 1930s/40s and it became the dominant design.
European marketing of washing machines also tended to cause an association between top-loading agitator machines and labour intensive, old technology that wasn't fully automatic as manufacturers pushed automatics, which were almost exclusively front-loading.
The preference for the 'built-in' fully integrated kitchen in Europe also had a huge impact. People like the idea of a washing machine that fits under a counter top, rather than a free-standing machine that sits in a basement. The ability to stack washer/dryer sets also made them more attractive.
When it comes to energy efficiency over here it's really a market decision, the inefficient products are labelled as such.
Everything's rated A to G (a = efficient .. G = grossly inefficient). People tend to buy A rated machines where possible.
Water's also charged for and metered in most of Europe which tends to ensure that people opt for more water-efficient machines generally.
So, the market does decide!
The very high spin speeds found in many European machines aren't necessarily something that needed to be exclusive to front loaders. I don't think it would be that difficult to come up with a very high spin top loader if it were a priority.
In general, Europeans tend to avoid tumble drying (higher energy costs and more environmental focus). So, washing machines that could hit anything up to 2000 rpm are rather more popular. Again though, it's marketing driven. For decades the spin speed has been a major feature of most machines to the level that many of them include it in their model numbers or have it emblazened upon their front panel. No self-respecting housewife would have anything that didn't sound like an Airbus A320 engine when finishing up her washing!
Also, I honestly think the porthole door has a major impact on sales here. Try selling a washing machine that you can't see the clothes in! People like to see things tumbling around and it's particularly impressive when your clothes go into warp 8 too at the end of the cycle
Market front loaders properly, and people will opt for them if they so chose!