Backups in DO are free only for now (until June 1st). Price will be 20% of what you pay for your VPS. Plus - snapshots will be 0.02$ per GB.
Plus DO bacukps does not happen every day and they are put on randomizer (based on load of backup system). For me every 3rd day is skipped.
Partly it's the UI. It's hard to tell how many snapshots they promise and what frequency.
Partly it's observations over the past week. I noticed a few days after moving that I had two backups the day I created my account, and no backups for 3 days after. Contacted support and was told they have some 'randomization for load balancing'. Asked what the worst-case frequency could be, and was told it's "usually 24 hours". This is the kind of thing that can bite you when the shit hits the fan.
(And the experience definitely shows what other commenters said about Linode's support.)