Upright exercise bikes often leave the store for far less than a comparable recumbent bike. The low entry price makes many sales. It's not just the low price though. See this style of bike offers more than just low price. There's more...
Many prefer the seating position. Not everybody likes the slouch recumbent ride. The upright feels much more like the road bicycle.
That seat becomes important since your whole body weight rests on a small area which can lead to pain. Also some back problems don't work as well with uprights as with recumbents.
If space matters, uprights just fit better. With a far smaller footprint, storage becomes easier and just using the machine does too. They fit more places than recumbents.
Mounting these may be better or worse. Recumbents mostly eliminate the getting over bars problems. They do have the down to the seat and back up issue. Uprights are more over and on, but sometimes there is some climbing over bike parts to do too. All in all, most uprights are easy on and easy off.
Back to price. The very cheapest exercise bikes often appear as uprights. Light, cheap bikes are junk. Move up to moderate uprights as the Schwinn 131 upright bike and the quality is there. Features are too. All the electronics and the drive quality work just like recumbents. It's just a different layout.
Cheap upright exercise bikes lack the quality to be useful. Better uprights rival recumbent bikes especially if you prefer the position and need smaller storage requirements.