The Courier 96 I sold had no levelling system. We used an assortment of 2X6s to drive onto. That got us close enough for me. Never really missed not having a levelling system.
The 5C came with a fancy system using electric solenoids to inflate or deflate each individual corner. Nice. However with a slow leak at the pass. side rear, by the next day we are not level any more and have to start the engine or the aux. compressor to correct it. I guess that would be the same with the wood levelling system, although that old Courier didn't leak. Oh, and a levelling system is another source of leaks and aggravation...
Some people are fussier than others about being level. My dear wife more so than me, LOL.
One advantage of air bag levelling over hydraulic jack would be the ability to raise the bus to get over a big transition (like getting onto a ferry), or lower it to get under a low bridge or into a low garage, if all you need is a few inches.
If I was building a bus, which I am not, a levelling system would be quite low on my list.