Actually I'm much more worried about Lemons & Nurses end up in the hands of a private aquarist - than a Sand Tiger. Either species is much more likely to end up in the hands of a private.
While - both Lemons & Nurses are very hardy species, they are also much easier to get, and fairly affordable for the price aquarist (if you consider a $600-750 shark affordable - as is the case with the Lemon).
Lemons are possible one of most dangerous shark that can end in private aquarist hands. Both Lemons & Nurses are well grow to 9-10'+, weight over 300 lbs and require huge ponds/lagoons of more than 1,000 sq ft & over 35,000 gallons.