Summons Issued 5 Days After Alleged Offence? Is This Legal?

A person I support had a summons dropped off at their home, 6 days after an the officer alleges that they saw them driving without a licence. Is this legal? My assumption would be that they would need to be pulled over to prove it was the person they alleged it was?

An officer has 6 months to lay a charge.

Sure, pulling over the vehicle is more common, but I don't see why it wouldn't be enough for a possible conviction if the officer could identify the individual behind the wheel.

There are scenarios where pulling over a vehicle isn't realistic for whatever reason (e.g. risking the safety of the public just to pull someone over.)

Do you mean driving without a valid license (i.e. suspended license) or driving without having the physical license on their person (i.e. left it at home)? If it's the former if the officer knew the driver and knew their license was suspended (maybe from a previous interaction) then I would say no. If it's the latter how would the officer know they didn't have their license with them if they weren't stopped?