I’m not surprised that its a low number.
I’m more surprised by the number of rockband instruments.
I remember when Codemasters confirmed there wouldn’t be a cockpit cam in Grid2 because it wasn’t worth the resources (considering barely anyone used it in the previous game).
If you skim through https://steamcharts.com/ you can see the sort of numbers racing games are getting (in terms of people playing).
Also keep in mind a few games, such as iRacing, run off their own client. But even then, iRacing boasts of 70,000 members.