I do think economies of scale plays a part, but also I expect the lack of choice is also a reason electric buses and coaches are still expensive.
Then there's the need for depots to have the infrastructure installed (locally, Uno buses have loads of buses still to be brought to site because a late change in charger requirements means they're still waiting to have the means to charge the new fleet - so they're running a handful of buses despite the buses all made and registered).
I also expect in the industry there are still lots of people in the chain that are not keen on EVs and actively seek to put people off, as well as protecting the sale of 'tried and tested' buses that are likely cheap to make now. Ongoing maintenance is presumably quite profitable, and electric vehicles usually need less of that.
I am not sure if it's a thing here in the UK, but many US car dealers have been found to actively lie to customers to put them off going electric so they can still sell ICE cars and ensure a decent income from repairs and maintenance.
All I know is that the few electric buses I've been on, they're quiet, smooth, and the powerful air conditioning was a godsend in the recent heatwaves. Drivers also love driving them, plus if they're not burning up there's less chance of an accident through fatigue.
I was surprised and a little disappointed when Arriva announced new buses and I found they weren't full electric.
On another note, I saw the Electric Viking (YouTuber) talking of CATL now selling batteries to end users for around US$65 per kWh. So imagine a 50kWh battery pack costing US$3250 (excluding casing, and presumably also requiring the cooling and BMS etc - although I don't know if the BMS would be included) and how much discount a car maker could be getting?
Imagine batteries for the home where suddenly you could have 30, 40 or 50kWh battery packs costing about half what a 10-15kWh battery costs today? These are the prices as of now too, and other makers are going to have to lower their costs. Will see instant price cuts? Maybe not (Fogstar is pretty cheap already though), and shipping fees may up the price for UK customers, but prices will fall and quite rapidly as more and more people are buying.
Plus, these are LFP batteries but sodium ion batteries should be even cheaper. While not likely to be used in cars, they'll be great for homes, RVs and caravans. Power stations, the type you might buy to go with plug-in solar when the next lot of regulations are sorted, should become way cheaper.
So, battery costs are now at a point where I can see electric vehicles getting even cheaper in the coming years. The already cheap Renault 5 now gets a smaller LFP battery option from later this year, and I expect these new batteries will appear in the all-new Dacia Spring and other Renault cars.
The Chinese will certainly be taking full advantage of the price cuts.
Also today I see Be.Ev is offering a new type of subscription, where you pay a fixed monthly fee and prepay for a set amount of energy to charge.. One plan being around £50 and offering 120kWh of charging that you just consume as and when. I don't know if they'll let you carry over unused power, as it's early days, but it brings the effective rate down to around 39-40p per kWh. Now if you can't charge from home, there are increasingly better options to charge nearby at a fast charger and pay rates comparable to your standard home tariff.
