Note that this is literally a publicity stunt. The flights offered are 30-40km (19-24mi) straight-line distance, and they are intentionally calling it an "experience". It's one person, no luggage, and only available for two months.

Maastricht has an once-per-hour train service to Liege which takes 30 minutes, and a twice-per-hour train service to Aachen which takes 50 minutes. The same can be done by car in 25 minutes and 45 minutes. Take into account travel to/from the airport, and it takes longer than just going by car or train.