As someone that lives in Atlanta, this is one of those things that is so obviously not true that it's not worth spending the time to point out the flaws in the study.
> We report an effect each day beginning the day after the policy implementation, 10 August 2019 through 22 September 2019.
The following March the scooters were effectively banned before returning later that Summer under a new permitting process.
I think they also need to discuss other projects which impacted commute times at the time. For example, major work on the GA400/I285 intersection began at that time. Changes to I75 and its dedicated pay lanes was underway. Those two routes are used by huge numbers of commuters every day and the impact was huge.
I supported two offices in Smyrna and Buckhead for a few years and lived in Gwinnett initially and relocated to buckhead after. I-285 sucked both ways in Gwinnett, but in buckhead, i was going against traffic, which made a friday commute in the rain a 15 minute drive home in buckhead. The logistics are much worse now.
I did happen to be in SoCal when the pandemic started and got to enjoy their highways with little to no traffic. I think I was only in like 3 or 4 traffic jams the whole time, when Atlanta is a traffic jam mon-fri from 7am to 6pm'ish.
When visiting Portland, the commute south mon-fri was always backed up during rush hour times (just like the good ole days), going towards Salem. Inadequate infrastructure from the 20th century makes some cities worse I guess.