Starting an EM group is a chicken and egg function - first, you need a fully functional group, ready to go, 100%, on a certain day. However, you also need a hospital or hospital group that has an opening for a group - meaning the hospital is either brand new, or have booted out the last, lock, stock, and barrel. If the second event occurs, you need a full crew ready to jettison any prior engagements at a moment's notice to jump in.
The difference between this and a dental or plastic surgery clinic is the only thing stopping the clinics is competition; a person can select where they will put their office, and, if there is a void, they fill it. That is not so with the EM group, and, mostly for it, EM docs have to work in locations they can't select.
I actually work in a new group, but what this group did was form a local organization with the same people, and the prior contract holders were "absentee landlords", and didn't have an option to send in more resources. The founding partners had to put up collateral, though, including, for most of them, their houses. Had it failed, they would have been homeless.