question about gta online servers and gta+

i know theres obviously valid reasons as to why this isnt the case but im wondering why there arent gta+ segregated sessions as an option? when you enter gta online you get put in a public lobby as usual but im wondering why there isnt an option to join a gta+ only session in the same menu where you can choose a invite only or friend only etc... as im sure it would be a lot less chaotic while still having a live population in the city.