Two driveway bids for the same house can be thousands of dollars apart, and both can be honest. The difference is almost always in the parts of the job you can't see once the concrete is down. Here's what moves the number.
The main cost drivers
Size. Square footage sets the base cost for concrete and labor. Small jobs carry a minimum because the truck, the crew, and the setup cost about the same either way.
Tear-out and haul-off. Replacing a driveway means breaking out the old slab and hauling it away. That's real labor and disposal cost, and it belongs on the bid as its own line.
Base and drainage. Correcting a failed base, adding gravel, and fixing drainage is often why the old driveway failed in the first place. It's also the part a low bid is most likely to skip.
Thickness and reinforcement. Four inches with a rebar grid on chairs is a different product from four inches with nothing in it. Thicker sections for heavy vehicles add cost and add a lot of strength.
Access and approach. Tight access, slopes, and work at the street apron all change the labor involved.
Finish. Broom finish is the durable, economical standard. Stamped or colored concrete costs more and needs periodic sealing.
What an itemized bid should show
Demolition and haul-off, base depth and material, slab thickness, reinforcement type and placement, joint layout, finish, and cleanup. If a bid doesn't mention the base or the reinforcement, ask. Those are the lines that decide whether the new driveway lasts.
Every Native Outdoor Living quote starts with a free site walk and comes back written and itemized, so you can compare it line by line.