Let's not forget the cost of the computer to plug these drives into. Also forgetting the management time for backups, and whatever offsite mechanism you're using for DR, whether it's just the price of gas to drive to a friend or family, the power at a second facility, safety deposit box, or whatever it is.
Nobody is saying that you can't do it for cheaper yourself, if you don't place much value on your time. Backing up 1TB at $.02/gb for one year costs $240. A 1TB external drive costs about $70, and we need at least 2 for redundancy. Assuming a 3 year warranty on the drive, and not accounting for any of the additional costs mentioned above, the total cost for 1TB over 3 years would be:
usb drives: $140
That's a difference of $580, over 36 months. In exchange for not having to worry about anything relating to my data's safety, in this scenario, I would pay an additional $16/month. Even if If I only had to spend, on average, an hour per month on the backups, I'd still consider the gdrive a better value, and that's not even considering the additional price of doing the backups yourself. All of the potential time dealing with whatever the DR solution is, re-syncing a failed drive and dealing with the RMA process, or any of the other countless issues there are with backups, I find the "cloud" solution works best for me.
YMMV, of course, which is why we all have options.