First off, I have now witnessed two people have very serious falls caused entirely by 4-wheel wheelie luggage.
I dislike the 2-wheeled type but they do a job. The 4-wheeled ones are inherently dangerous.
I helped a lady down from a train yesterday, she was settled on the platform, I and another person thought. But she misjudged reaching for her bag. It of course gave her less than no support, as it rolled and tipped the moment she put her weight on it. Result: full face plant.