Sometimes it's not free! Buying a coffee every few hours to seem like you are not just hanging around can add up. Though this is cheaper than coworking, productivity may may not reach its full potential. In a coffee shop, you have people coming in and out, noise from the espresso machine, limited deskspace, a set timeframe to do your work, sometimes there is no space at the shop, you can't leave your stuff to go to the washroom. At a coworking space, these problems are solved. You are able to have a dedicated workstation you can make your own, leave your stuff to go out for lunch. If you need to meet any clients, a meeting room is available too. Since your company is at a permanent address, (potential) clients can see you're professional and trustworthy.
Coworking costs more than a coffee shop but is low enough to keep business running and raise productivity.
Noisy cafes can make you lose focus and in a coworking environment, you can bounce ideas off peers and collaborate with like-minded entrepreneurs.