So if we are talking about 10+ years long term outlook: income will only be as high if Tesla's solution is going to become a de-facto monopoly, and they can price their taxi services to around the pricing of human driven taxi services.
Otherwise if there's competition then robotaxis will set the price of taxi services to below that of human taxi services, human taxi services will gradually die out and robotaxi services will conduct a usual race to the bottom, prices somewhere around the price of expected capital returns.
I.e. the very long run lower price target for a $50k capital investment will be ~5% of the capital, $2.5k/year, or $25k over 10 years.
But in the initial phase they will track taxi services pricing, and will generate 10x higher returns - especially if Tesla becomes the dominant leader in the segment, which they have every chance to achieve.