There is only a common spelling difference in the written sense though. An American would not fully understand someone from Yorkshire speaking Yorkshire dialect, nor would they understand someone from Merseyside, Glasgow, etc. if they were speaking in their dialect.

I'm from Yorkshire originally, my dialect is totally different from those in Merseyside or the North East (for example.) How we speak and how we write is different. 'British English' only exists in the written form and I don't believe that is what this service is aiming to 'improve'.

UK regional accents/dialects are something which are favourable. The North East dialect, for example, is seen as favourable in call centres because the majority find it a 'nice' or 'friendly' dialect.

I don't understand the idea of 'if you're a start-up don't have an accent/dialect'.