Regulatory
A key difference between mobile networks and WiFi is that is mobile networks more often than not use licensed radio spectrum and with access carefully coordinated. As such it is typically necessary to obtain a spectrum licence from the wireless regulatory body in your country.
Fortunately, whereas once cellular spectrum was largely the reserve of mobile network operators with national licenses secured at great cost, it is increasingly being made available for use with much smaller private and community networks via low cost licensing schemes.
Another potential consideration is compliance with limits on electromagnetic field (EMF) exposure for the protection of the general public. Though this may only be applicable with higher power transmitters and many private mobile networks will be operating “small cells”, with RF power levels far below those used by the connected UEs which are carried about persons.