However, in offer paperwork, it will sometimes be stated as a dollar value. This is for two reasons: the first is that RSUs need to be approved by the board at a meeting, which can happen some time after the hire date, at which time the dollar value is converted into shares.
But the main reason is that it makes it easier for the candidate to understand the value of the RSUs, and lets the company then talk about the total compensation and try to treat RSUs like cash in that discussion.