How many customers use more than 1GB of outbound traffic per month for a $5 server? Data transfer in is free on EC2 and the first 1GB outbound is free too according to the pricing page.
Isn't the first GB of your account traffic free with AWS vs DO giving you 1 TB per droplet?
While 1 EC2 instance may not use more then 1 GB (which is a very low quota unless your CDNing everything), if you have a couple of instances your almost certainly going over that.