Being a professional driver (even aided by GPS and Waze) and speaking fluent English are absolutely valuable skills on the US market.
One in five US residents speaks a language other than English at home. Of those that speak a language other than English, only 58% speak English "very well" Older people are less likely to speak English "very well" than younger people. https://www.census.gov/prod/2013pubs/acs-22.pdf
So when you're looking at the bottom 10% or so of the workforce, speaking fluent English is a HUGELY marketable job skill.
And if you want to drive for Uber, you need to meet Uber's requirements. You need to be 21 or older. You need to have 3 years of driving experience (you can't just go out and get a license if you decide you want to drive for Uber). Clean driving record, background check, no criminal history at all in the last 7 years...
You need to have a clean 4-door sedan in good condition that can pass an inspection.
Even if you manage to jump through all those hoops, driving for Uber can be customer service in the extreme. Sure, I can drive myself to the grocery store and back like a champ, but Uber drivers are driving on unfamiliar roads to unknown destinations every day. And they're doing it with a paying customer in the backseat. I live in Boston, and there are certain sections of town where the GPS routinely doesn't work/jumps around, and those sections happen to be a minefield of winding one-way streets and construction.
How do you deal with GPS issues? Surprise construction? Traffic that Waze didn't predict? How do you mollify customers when things go wrong? Can you drive defensively and still make a timely arrival to your destination? I've taken a lot of Ubers and have seen some REALLY bad drivers, and some really fantastic ones that handled the car like a pro.
My point is, working as a cook at McDonalds requires far fewer resources and job skills than driving an Uber, hands down. You could make a more compelling argument for working the register, but cooking fries is trivial and requires very few skills or resources.
Knowing how to drive is nearly ubiquitous in the US in the 18+ year old population.
So, let's say the metric is "additional training required after age 18".
Driving: likely none. McDonalds: likely a little!