I think you are just seeing patterns where they don’t exist.
These online casinos don’t need to use algorithms or “fix” the software because a strong house edge is built into roulette already (2-5% depending on number of zeros).
The “give 30% and take 70%” you suggest is not necessary for them. Those 2 green zeros are all they need to consistently make a profit off you, so they have no need to “fix” their roulette.