Fly isn't implemented out of battles for a simple stability reason: imagine a whole server teleporting around as much as they wish to. Paying the teleportation makes it less used. Also since you talked about inflation, Subway and Transit can be seen as a money sink to take off a lot of money from ingame and so reduce inflation, this is basic economic, more money you got on market worst will be inflation.
TLDR: Weekly ticket will help for inflation and will generally help people travelling around such as daycares and sellers.