Nobody outside of Microsoft offers it for free (and that's only because they own Azure). Cloud servers cost money to operate and maintain, of course you're not getting it for free.
Azure has nothing to do with it given it was a thing before Azure was a thing. And as for Sony, they don't
delete all your cloud saves just because your PS Plus subscription has lapsed.
At the end of the day, we're talking about tiny amounts of data for cloud saves. And this is something that can easily be covered by the investment you've made in the platform itself, and the licensing costs Nintendo gets from physical sales, and the cut they take from everything sold via the eShop - not to mention those that do subscribe for online gaming will add money to that pot too.
All that aside, perhaps we should be thankful that Switch has cloud saves at all.