While your concern is still totally valid, if a civilian mistakes a 747 for a drone and shoots at it with anything but a laser, they’re gonna miss lol. It will probably be out of range in fact.
In other words, if you’re within 1km (0.6 miles) of a large passenger jet, you’re absolutely not mistaking it for a drone.
You clearly haven't seen the videos of people that are just clearly observing large passenger jets coming for a landing for a drone. Also, they probably will miss, but that bullet is landing somewhere. A plane coming in for a landing pass was just shot at (and hit) recently in Haiti, so it's not impossible.
In other words, if you’re within 1km (0.6 miles) of a large passenger jet, you’re absolutely not mistaking it for a drone.