Most people rely on their host to perform backup for them. In fact it should your own responsibility, here is why…
Hosting company do backups of your site for their benefit.
eg. if the box crashes completely and they need to restore all the sites
from that box onto a new one.
All of the files from all the sites on that computer could potentially be jumbled
together on the backup.
Also you have no way of telling when they take a backup and which backup they will restore.
Basically their requirements for keeping backups of your site are different from your requirements for keeping a backup of your site.
If you were to accidentally delete some files from your site and then asked your host to restore them for you then if they were able to locate a suitable backup and restore it for you then they would be justified in charging you for that service since you are
taking staff away from their regular responsibilities to perform a task
that is really your responsibility.