Most calls start with a lot that's letting the owner down. It might be gravel that ruts and washes out every time it rains, old pavement breaking up where delivery trucks turn, or an office, church or rental property that's simply run out of spaces. Each of those tells me something about the traffic and the ground before I measure anything.
The price moves with the size of the lot, how thick the concrete has to be for the traffic, and how much ground work it takes to get a solid base under it. The schedule turns on any permits the site needs, the prep, and the days the new concrete stays closed while it gains strength. For your own numbers, that's what the on-site estimate is for.
Mississippi requires contractors doing commercial and residential work to be licensed by the Mississippi State Board of Contractors, and that applies to anyone you hire for a lot. A lot also has more people with a say in it than a driveway does. Engineers size it, the city and sometimes the state sign off on it, and we build it to what they set.