Transport ministry inspectors, being civil servants, finish work at 5pm, leaving the door open to pirate cabbies.
Fines totalling 80,000 euros were issued against pirate operators at Palma airport.
The pirate taxi drivers have each been fined 6,000 euros.
Fines for advertising pirate taxis via websites could be as high as 12,000 euros.
Sixty per cent of checks were because of the campaign to stamp out illegal transport providers.