No one did behests because their rewards sucked.
No one did sidequests because their rewards sucked.

No one's going to do the Company leves/expeditions/supply/provision quests because..

You guessed it.

Their rewards suck.

There's a defend a scholar company leve in Cassiopeia Hollow. You defend an NPC for a solid 15 minutes straight. Seal reward?

40. 40 seals. For a 15 minute duration and a leve allowance.

The supply/provision quests? 3 iron ingots for 6 seals? Really?

The expedition? Good luck on finding anyone to do that quest with. From what I've heard, it's not much better, players earning anywhere from 25-80 seals a 20 minute run.