My belief is that it's easier to get away with because the testing is intentionally lax, as compared to other sports, in combat sports the money is closely tied to specific individuals. In a team sport say football, if someone fails a test then the team will lose some revenue, but the player is simply replaced and the team still plays its allotted games every year, still gets its guaranteed TV money, etc. Even in other individual sports, say athletics, it's not as big of a financial loss for an athlete to fail a test. If Usain Bolt were to have tested positive before the Olympics, people would have lost money but you still have your prestigious 100m final. In combat sports, the event is closely tied to two individuals. In McGregor failed a test before fighting Khabib, then there is no event and no money. It is in the interests of those running the show that things are swept under the rug.
