Suff, I think you might possibly have missed the point the First Leeds rep was making.
On the most heavily trafficked routes the buses run every ten minutes or less at peak periods, and the buses carry adverts to that fact. Those buses then run to the same timetable throughout the day and, certainly in Leeds, they remain well used. That is also the case for the less trafficked or minor routes. There simply is not much leeway or room to build extra capacity, not least because of other road traffic.
When it comes to drivers the company already uses split shifts and 'spares, for extra cover - a neighbour, now retired, was one. And let us not forget that drivers are expensive. They are not burger flippers or coffee makers (baristas) who can be trained up on a two day NVQ course. For a car licence driver you are looking at a ten day intensive course, then a test at something like £2,000 a go. Then there is specific company training for things such as taking fares and giving tickets, checking transport passes, giving timetable or route information and helping passengers with mobility problem. And they have to keep their hours up or be re-tested.
With buses the costs skyrocket. A decent double decker bus costs about £200k. It needs servicing to very high standard by techies with good qualifications. More buses requires more of them, and at some cost. These extra buses need garaging or parking up when not in use. And how many would be needed to make a big difference to a city the size of Leeds, Birmingham or Bristol, 10 (£2m), 20 (£4m), 50 (£10m)? With an average of 77 passengers per full bus I am thinking that an extra 50 buses (3,850 passengers) would not cut it. Scale up whatever numbers are needed countrywide and it comes to a sizeable chunk of cash.
The other forms of vehicles and practices you mention will one day come in and prove very worthwhile. I absolutely agree on that, but they are for the future when the problem is now. There is one thing that I do know and is that bus companies cannot 'force' people out of their cars to use their services - no matter how comfortable and efficient they are. That is going to need a mighty shift in the way society operates.
Kaz, do NOT mention the qualifying age for a pass to many female members of my extended family.... they could form a lynch mob all on their own. I remain surprised that the changes did not go the same way as the Poll Tax.