“Halving” vehicles has been possible for long time, also seen it mentioned numerous times over the years. Unless large & small vehicles never use the same roads, ever, it will never happen; imagine being in a small car and being hit by a large car, odd of person in small car dying are much higher. Basically, something like this will only have a chance in an authoritarian society.
As for the RV, you still need parking and most people don’t want to live in the middle of nowhere. Most cities are already strict on RV living, especially long term local RV living; if it became even more popular, they would become even more strict. RV also are impossible to insulate, as a result, frequently follow the weather; majority of people don’t want to be constantly driving around to find and adjust to a new location.
As for the RV, you still need parking and most people don’t want to live in the middle of nowhere. Most cities are already strict on RV living, especially long term local RV living; if it became even more popular, they would become even more strict. RV also are impossible to insulate, as a result, frequently follow the weather; majority of people don’t want to be constantly driving around to find and adjust to a new location.