Professional APs are in the $1-2 thousand dollar range, and you need one for every 5ish users. So, for a small company of 20 people (which won't have it's own IT professional), you're looking at an initial outlay of between 20 and 40 thousand dollars (IT contractors are expensive, and you have to include the Ethernet drops, rack, routers, patch panels, labor, etc), and a few grand a month for maintenance and support.
Compared to using plain Ethernet drops, the cost is hardly negligible, to the point where it isn't worth it for many companies.
My company has been going through the process of implementing this for a new office to hold around 100 people, and the amount of planning required to provide good coverage at a reasonable price has been enlightening to observe.
> Heck, your $30/night Motel 8 can manage that...
Not in my experience. At least not well enough to support bandwidth above the 100Kbps range.