... because their job is so easy.
That depends on the job. Simple transactions are easy. Multi-sig isn't as easy, and multiple addresses involve more work, and ICOs or holding dev funds and bounty payments and all that involve even more work.
LOL! Their job isn't so easy at all. There are escrows that are even working with companies that are entrusting them with hundred of thousands to millions worth of bitcoin. And there's a lot of work for them to secure that amount will be secured. As Dabs said multi sig, bounty payments and other tasks that are related to the contract if there's any. Before I think I can be a potential escrow but later on understanding the true nature of being an escrow, I stopped thinking about it anymore.