Few years ago I started to notice that there are digital products which’s mobile apps are vastly more usable than their desktop alternatives.
Take PayPal. Their website has been recently redesigned, but even now so many things are presented at once that I’m lost. And their mobile app: beautiful, fast, concise presentation of just the features that matter.
Or eBay. Their website is very crowded and complex. And the mobile app? Again: modern, fast, concise.
Another examples would be Microsoft Outlook, Amazon, various German banking and transportation apps.
I think these mobile apps are better because they had less legacy to support and the screens are much smaller. The competition, and thus demand, for good UI is also more intense on mobile.