That's a real service. Some airports, including LAX and London Heathrow, allow a "tarmac transfer", where the limo goes directly to the plane. [1][2] Cost is $200 to $1000. That could save an hour or more at each end.

VIP Terminal Access: Skip the standard queues and enter exclusive VIP terminals where you’ll receive expedited passport control, security checks, and personalized services, all while enjoying luxury amenities. Avoid long security lines with expedited security processing, ensuring you spend minimal time in the airport.

[1] https://limossist.com/tarmac-transfers/

[2] https://airssist.com/airport-tarmac-transfer-service/