Also, people buying rental property from cash they earned from wages or selling their business pay tax on the wages/gains and the rental income, not just the latter...

You can also sell it and take the gains tax free in many cases.

Short of a 1031 exchange, I'm not sure how you would do that.

You can sell a house every 2 years and write off up to $500k in capital gains as long as it’s been your primary residence for 2 of the last 5 years. Doesn’t need to be consecutive.

Sure, but you have to stomach the 6% commission you’re paying to the brokers, which really limits this situation to transitory market conditions instead of a get rich quick strategy.