Very often I booked hotels online while standing in their lobby. It’s much cheaper.
I’ve flown those cheap local airlines. I draw the limit when they have duct tape on the broken window.
I used to fly Ryan Air quite a bit. The discount flights were cheaper than a taxi ride. I remember flying Dublin to Berlin for 10 Euro. You felt like cattle as they herded you across the tarmac and up a set of steps into the plane. No assigned seats, just pile in.
Yet when going to concerts, it works the other way. Booking online gets you many fees (Ticketmaster), while buying at the gate saves money.