I've switched between ISO and ANSI boards a lot during my years using computers, which has affected my typing habits. I now use right Shift exclusively as a result. However, I use ANSI exclusively on my customs / mechanicals, mainly for keycap compatibility, but I also prefer the aesthetics of ANSI.
ISO layout does have a lot of users, but there are so many ISO character layouts, whereas ANSI has less. So a manufacturer can target a bigger market with a single ANSI layout. If they do bring out ISO layouts, they tend to focus on UK, German, French and Nordic layouts in that priority, but since there are so many possible layouts, some just use UK with extra characters front printed on the relevant caps.
Pok3r and Ducky Mini are the two most common 60% boards that come in ISO.
Many users of mechanicals in Europe have done the same as me and switch to ANSI, though, since it doesn't take much adaptation and the options are much greater.