A quick google shows that this is pretty common in the UK. And it seems to me that article 43 of the industry body regarding liquid gas causes a lot of that confusion for any of its members, including the distributors and providers of such gas.
Back in the Netherlands I used to run it, as did my parents. Just don’t think it’s really worth it anymore and the dis benefits far out way the small cost savings.
I wouldn’t have a vehicle with it myself in this day and age. Won’t be long until it’s removed from all forecourts and only available from specialists.