Most online airport-transfer brands you'll find for Stuttgart are aggregators — they take your booking, mark it up, and forward it to whichever local taxi accepts the lowest payout. The driver who picks you up has no contractual relationship with the brand on the booking confirmation.
We're the operator. Stuttgart Taxi FB GmbH holds PBefG-licensed taxi concessions (§ 47 Personenbeförderungsgesetz) issued by the city of Stuttgart; every driver is on our payroll under a German employment contract; every vehicle is in our own fleet (Mercedes E-Class, V-Class, S-Class). The managing director is a board member of the Stuttgarter Taxi-Verband (STV) — the regional association that represents the licensed taxi trade.
For your travel managers, that means three things in practice: one entity to invoice, one entity to escalate to, one entity that's legally accountable if the service falls short. No aggregator-to-subcontractor finger-pointing.