Situation with speed bikes is odd because of their need to have registration, licence and in particular insurance, and also the fact that they are illegal off-road in any public place (bike path, bridleway etc). This makes them quite unattractive as a bicycle alternative. As there are relatively few (and even fewer being ridden legally) it is an insurance niche that is very poorly covered, and I gather pretty expensive when you do find it.
Nevertheless they clearly have a role to play, especially for commuting. It's a bit chicken and egg; when there are more, and it is easy to establish which profile of riders is riding them responsibly, then insurance will become easier and cheaper. Then more people will buy them, so the bikes will become cheaper (even without subsidy). I can't see subsidy coming until they are more established than they are, or even any significant relaxation in the rules relating to them.