It's not that there are more remote jobs in Scala than in Javascript. However, people who hire Scala developers seem to accept that when you need a top Scala team, you have to bring people from all over the world, i.e. they are fully committed to building a great fully remote team, not bringing remote developers as an afterthought (in general, you wouldn't want to take a role of remote engineer in a mostly non-remote team, especially if you are one of the first ones).
And Python/Javascript developers are dime a dozen (maybe not, they are still expensive, but much more numerous, and usually there isn't a problem to hire locally).