Welcome!
Where is the project located, and what is the applicable building code?
Out here in California, our own adopted code is based on the 2021 International Building Code, which defines this in section 202 as follows:
PUBLIC WAY. A street, alley or other
parcel of land [1] open to the outside air [2] leading to a street, that has been [3]
deeded, dedicated or otherwise permanently appropriated to the public for
public use and [4] which has a
clear width and height of not less than 10 feet (3048 mm).
So a parking lot might or might not be a public way, depending mostly on its underlying ownership or dedication, its eventual connection to a street, and also depending on its minimum size.
Whether or not it is used for parking or for other purposes is irrelevant.
Note that "leading to a street" does not say that it must be a vehicular connection. It could be a landscaped area, walkway, etc.
Note that there is nothing that requires the parking lot to be part of a means of egress system. If you are the designer, the choice is yours as to how to get from the exits to the public ROW. It could be through a parking lot, or it could on a walkway through a grassy yard.
Lastly, I notice you posted this in the thread called "Building Code and Construction Related ARTICLES". This is typically where people post about news stories or published articles. You may get more responses in the future if you put this in the commercial codes forum.
