Unlike the NetEnt centrally controlled the software and rigorously picked operators' practice, Microgaming slots are individually procured by the operators with no further tangible liability for doing fair business after the acquisition, i.e. the casinos have the opportunity to tamper with the games, once Microgaming seals the deal.
In the former times, Microgaming were handed out almost for nothing, which at that point diminished the developers’ evident achievements and the manufacturer’s reputation. In this sense, having games priced so down for many shady just launched casinos was an easy way to close the entire establishment rather than to pay some big win.
Moreover, licensed slots are supposed to work equally in DEMO and REAL money mode. There is no certainty that if you perform your tests on specific slots by other than NetEnt developers, you will have identical software once you start playing for real money.