[kyrra]

Most companies do stock buybacks as a way to pay out bonuses to employees and execs with a lower tax rate. Since RSUs are taxed lower (I think), companies pay employees with those. But those grants are given by creating new shares. To not dilute the value of these shares, the company needs to keep buying back shares.

[basiccalendar74]

RSUs are treated as cash income at vest and taxed at same rates.

Stock buybacks benefit general shareholders (i.e. beyond employees) since they push up stock value without causing a taxable event. The alternative is dividends which are immediately taxed.