Shareware disks _could_ be written and paid for by the shareware author, but user-to-user distribution, at the _user's_ cost was [seemingly] more common.

I recall my local independent PC shop in the mid-90s had a big assortment of shareware on 5.25" floppies, priced per disc. Similar offerings existed in mail-order catalogs. The disc provider made a small margin per disc, presumably, and it created a different distribution network for the shareware copies, in an era pre-ubiquitous Internet.

A few years later, there were shops that specialized in burned or pressed CDs of Linux/BSD distributions back when dialup was the standard and fetching a few gigs of Debian was out of reach.