The teleportation by the Mages Guild is instantaneous, always the same price regardless of distance or bargaining ability, and available to non-guild members. How would the Silt Striders get any business on routes between cities with Mages Guilds, like Balmora to Ald'Ruhn? Wouldn't economics suggest that they would have to lower their prices to compete?
- No monopoly for the mage guild. Caravaner being a Dunmer bulwark they are not likely to stop travelling just because the mage guild stepped in.
- Trade goods... try to get loads in and out of the mage guilds... The mages will quickly put a stop on that. Uppity figures that they are.
- Different destinations. No mage guild in Seyda Neen for example.
The price goes down when the disposition of the caravaner goes up as well. BTW you can also travel by boat. Likely a some pocket money with the main activity being piracy, that.