Or even free.
When I was in the Seattle tech scene about ten years ago, the State of Washington had free co-working space at the convention center as a way to stimulate local entrepreneurship. The desks were a little strange, but they were free!
But even living in Boston I never saw the libraries super packed, usually plenty of room in the top-floor old-school reading room at the central branch on Boylston. Maybe not on holidays, but those sucked for cafes too in the city–better to just stay home or not work those days.
Internet can be a crapshoot, but I can do most of my work tethered to cell anyways. I always have that one cafe with awesome WiFi I can go to for downloading OS/IDE updates.
At least it's nice to know people are using our library.
1. At a library, when it's poop time, you gotta bag everything and bring it with you. Mildly annoying if you're using a mouse and notebooks etc.
2. If you're in a major metro library, no matter how hard they try to keep it clean, the bathrooms are full of people using the sink as a shower, and the toilets are foul beyond measure.
Your local library. It has desks, internet, restrooms. And there are more than one so you can pick the one that best fits your needs.