Such as? ADL, Wright and Switch all produce their own chassis and bodies. The only option is a European body builder, or possibly MCV.
When you actually look at it MCVs market share is fairly limited.
The only reason the eVoRa has done well is because there's not any real competition for it, it's pretty much the only mainstream full size single decker, discounting the new Wright offering. Even then they've on average built 40 per year, so while it has done well, it's not a "roaring" success that has shook up the industry. ADL can and often do put out that many E200MMCs in under a week.
Likewise over 1/4th of the EvoSetti sales were for London B5LHs, none of which have been built for almost two years. Only two B5TL examples have been built in the last 3 and a half years. They're without a doubt seeing far more success in HK where around 80 B8Ls have been built in the last year.