A consistent low maintenance track is what you get from onroad racing. If you race on carpet tyre wear is non-existant too. If those are the things you're looking for, why not race onroad?
There's the added advantage that if you're looking to race in a comfortable indoor environment a rollout carpet track will provide you with a satisfying layout in a smaller area if you race 12th scale.
It's true the UK has some outdoor astro tracks. They exist because the appalling weather conditions in the UK make dirt running really difficult. They also do a lot of racing on grass in the UK – which has most of the advantages you're asking for from astro but does actually develop like a proper offroad surface. Here's an example:
https://www.youtube.com/watch?v=dbHH9DUwjIA It also has the advantage of being easier to come to grips with for a beginner and being very low outlay.
The same weather conditions that result in some outdoor astro tracks in the UK, also produce ~100 indoor rollout carpet clubs. The 12th GT class is booming in the UK right now, some there even reckon it's saved RC from a slow decline in the UK.
The point is there are already track conditions (grass) and classes (indoor onroad classes) that do everything you guys are saying you want from offroad astro, and do it better. Given that, why insist on something that doesn't have what a large portion of offroad racers say is fundamental to their enjoyment of the discipline?