I've been listening to 142.740MHz all day. RadioReference says it's a Thorold FleetNet tower, but I've been listening to EMS calls from Brantford, Etobicoke, Oakville, and Missisauga. Am I missing something here? Located in St. Catharines.
EMS in that region uses the FleetNet trunking system. EMS on that system is analog. When you sit on any of the of the frequencies of that system (not including the control channel) you may hear analog EMS or any other analog transmissions from other agencies on those frequencies.
Look where Oakville and Mississauga is, there is nothing blocking the signals crossing the lake. When I travelled east into Halton, Fonthill was my go-to tower for FleetNet because Mississauga, Hamilton, Niagara CACC EMS radios all affiliate well.