When architects manage a job,they hire the engineering student firms to help. Things like a subway station is generally run by the state so the engineers will also estimate the job cost for their discipline. This could be either to check the estimator or to check the bids coming in.
In small scale commercial. The chosen contractors and subs will bid the jobs and the engineers will not estimate the job. This boils down to money and cost. Large per companies know what builders or contractors they want so won't spend the money on having expensive engineers estimate their costs. Of course they will be asked their opinion on the price from time to time.