Most public work is hard bid. The owner opens the bids at a set time, often in public. Price decides, and there is little room to negotiate.
Example: a school district takes sealed bids from general contractors. Each general contractor uses the lowest complete price it has for each trade.
On a hard bid, your scope must match the documents exactly. A missed item comes out of your profit. An extra item can lose you the job. Send questions before the RFI deadline. Read every addendum and keep your exclusions short and specific.