It isn't as if the OTT guys don't have fees too. Adding fees to give you a usable DVR and additional streams are just the beginning.
I would associate extra costs for multiple user access (streams) more with cable/satellite than with OTT services. Is there any cable company or satellite service that doesn't charge for box rental and service on a second and third (and fourth, etc.) TV? And how many of these offer free access outside the home, anytime anywhere, without extra costs? Sure, Dish has Dish Anywhere, but for full access, don't you need a Hopper 2 or 3 (and the extra costs associated)? With Cox Cable, I needed the $30/mo. Contour upgrade (before box rental) to get access to my channels and recordings anywhere outside my living room TV.
Each OTT service does have certain quirks and limitations, but you basically get at least two simultaneous streams (sometimes 3 or 5) anywhere in your home and often outside the home included in the base package fee. With YouTube TV, for example, I get full access, including recordings, in every room of my house, anywhere within home Wi-Fi range, and I could have a couple of other people watching at the same time (with their own viewing profiles), for $35/mo. I'm pretty sure I get full access outside the home, but haven't tried it yet.
Bottom line for me is the biggest savings from OTT live TV services comes in accessing my service anywhere without paying a penny more.
I'm not saying some services don't charge extra for even more simultaneous streams, but that's just to prevent people from sharing/selling their login info too widely. It's really a non-issue unless you have a large family.