The blanket jamming of a range of frequencies is against international agreements, so would be highly illegal. Law enforcement and the military may exercise limited exemptions when dealing with specific incidents such as suspect packages.
The majority of drones use the same band of frequencies as wifi internet routers, so jamming the airwaves around airports would deny local residents use of wifi. In any case the drones use complex software algorithms to be able to receive (and transmit) control signals through heavy interference. Even the cheapest toy drones will automatically tune to the clearest, most interference free radio channel while pairing with a controller. Most will also automatically change frequncy to another channel if the control signal is lost for any reason.
The actual radio transmitters and receivers used are mass produced and not particularly well tuned. Tolerances are a bit broad as you might expect with items built to the lowest cost. However these shortfalls can be countered by using software to filter out the wanted signals from interference and jamming. It is far cheaper to write some computer software than spend money on tight engineering design.
Jamming signals are just not effective in modern digital radio systems.