You need to make sure you spawn at the right parking type.
There are multiple different types of parking types and they need to match with the appropriate aircraft type as well. If you’re flying on the Airbus, You will only get pushback tug when you spawn into Gate Heavy/Medium/Small, or Ramp GA Large/Medium. If you spawn on Ramp GA Small, you won’t get the pushback tug.
Same goes with other ground service vehicles, If you spawn on GA Ramp Medium, you would only get Ground Power Unit and Baggage. You won’t get Catering, or Stairs. On GA Ramp Small, you only get Ground Power Unit, and nothing else.