I've done some testing of my own on microgaming and playtech this past week.
I basically did this, I flatbetted on the even outside bets one after the other. I bet one unit on 1-18, then after this I bet one unit on even, then one unit on red, then one unit on black, then one unit on odd, then one unit on 19-36, then went back in reverse, from odd, to black, to red, to even, to 1-18 and then forward again. I basically just flatbetted on one outside bet, moving from one to the next after each spin, and didn't change my betsize at any point. Sometimes I experienced long losing runs, other times I experienced long winning runs, and other times it was a zigzag experience, but it all seemed to level out. It was extremely boring, but after what must have been thousands of bets, I ended up with roughly the same starting balance give or take a few units and hadn't really lost anything.
The results of this experiment seem to show the RNG was fair...
It got me thinking that perhaps the reason online games are so difficult is because they are random. If something is completely random it is impossible to predict the outcome and therefore impossible to beat. Therefore I think a software developer and casino operator would be keen for their games to be as random as possible... randomness is a casinos friend. So it doesn't really make any sense for them to rig the games...