I have used hanger racks for decades. In the 70's, they used c-clamps and bolted to (and sometimes bent) the bumpers of my cars. In the 90's, I started using hitch mount racks, 2" on a Jeep SUV and 1-1/4" on a tiny Miata. I carried one or two bikes many hundreds of miles on these racks. Those bikes were not lightweights either. They weighed 30-35 pounds. I still have some of them, so I know the weights.
As those hitch type hanger racks probably carried 70 pounds in their day, they could surely hold one 50 pound bike. However, some bikes aren't good for hanger racks. Step-thru and women's bikes that need a beam that hooks between the handlebars and seat are poor candidates for me. I don't trust the quick release seat clamps not to come loose and drop the bikes. Also, some of my racks had two arms, but one had a single arm with a clamp, and the bike had to balance on that one point. A bike with a hub motor would be unbalanced and stress the clamp.
It's mostly common sense though.. Am I going to hang a couple of thousand bucks worth of bike on those racks and maybe stress the frames, or do I want them sitting on their wheels? Wheels for me, even though most of my ebikes could be hung.
I ordered a platform rack. It looked secure and I didn't have to lift the bikes very far. Then drat, I found out almost every one of my bikes, even the older ones without motors and batteries, exceeded the 35 pound/bike weight limit on my 1-1/4" Swagman XTC2.
I think one can get by with a 1 1/4" hitch rack for one lighter ebike, but for heavier reliable carrying one needs a big car and a 2" rack.