As far back as I can remember, the basis reported by my broker on my 1099 for vested RSUs has always been $0. Every year I receive a letter informing me that my broker is legally not allowed to report an adjusted basis that accounts for the fact that the RSU's value (at vesting) has already been taxed as ordinary income. Every year I go the the broker's website, find the actual adjusted basis numbers, and report that to the IRS. This seems perfectly unnecessary. Furthermore, less financially attentive co-workers end up paying ordinary income tax AND capital gains on the value of their vested RSUs.
Schwab sums it up nicely here
"Since tax year 2015 regulations and moving forward, regulators have required brokers to report the award price (i.e., the price at which the award was granted to you). Brokers are not allowed to adjust the cost basis for shares for which ordinary income has already been recognized. The responsibility to adjust now falls to you, the participant."
Where can I find this law/regulation and what is its motivation? I assume it's not simply to trick people into paying double taxes on their RSUs.