Yes, it's a problem in vanilla, which is why I use Transfer Manager CE to limit their reach to airport area. They will travel the roads leading out of the area, so it's important to give them a chance to turn back once their leave, otherwise they may have to go all the way to the city to turn back. I also use Vehicle Selector to spawn all airport vehicles from a single depot and skip generic ones.
But please don't think I'm lecturing you! I just wanted to share a trick I learned recently and suggest making vehicles compatibles with it. These assets are amazing and obviously still work fine the way they're now.

Yes, security vehicle updates are coming eventually
And they were chosen as buses to have more control over them, as road maintenance would just end up traveling around the map in most cases

Fantastic, thank you! Exaclty what I need for my airport <3 Will you add airport security and other utility vehicles as well?
BTW setting them up as maintenance vehicles/snowplows would make them ride the around the airport on their own and actually do something other than just making traffic, much like Ryde airport security does when set as police vehicle. Did you consider adding this as an option?

it contains props already

Awesome! When can it be made into PROP?

What grass does the airport use? Please recommend it.