"Income" is so much a part of investing nomenclature that it can be easy to miss important distinctions. Most mutual fund companies and almost every retirement plan offer some form of "income fund" or "growth and income fund". But the return from these investments fluctuate based on market performance, interest rates, or the performance of underlying securities like bonds.
There may be goals for income, and there are certainly benchmarks, but there is no guarantee of receiving returns. A fixed annuity, however, guarantees an income stream that a person cannot outlive. Only an insurance company like TIAA can offer this form of guaranteed lifetime income. Keep in mind that guarantees are always subject to the claims-paying ability of the issuing insurance company.