Microsoft is the second largest company on Earth and they take BTC. 
yet bitcoin adoption is growing at a very slow pace because there is a need for shops that people uses regularly everyday to accept bitcoin, for example a food company like tesco in the UK or walmart in the US or amazon / ebay etc...
microsoft is a big company but their product are designed for only a small % of the population
Sure. We will be growing for years still. But it is easier than ever for me to find what I want in BTC. And actually, some Ebay retailers do take bitcoin.
It's sometimes not feasible for big companies.
And it's sometimes not useful to small local businesses.
And it's sometimes not useful to small local businesses.
I disagree. I set up bitcoin for businesses and they are shocked at how easy it is. There is zero barrier to entry and it is free to use. Using a service like bitpay the business faces no market volitility and in fact companies big and small make about 3% more in profit than if the customer uses a credit card. There is NO downside, no risk. All you have to do is say "we take bitcoin".
How do Bitpay handle the BTC volitility? It could be that the competitor payment processors are using the BTC volitility as leverage to discourage companies to accept BTC
Most people do not even know about Bitpay and with all the negativity surrounding BTC, people could easily be convinced that volitility is too big a barrier to accept BTC as a payment option.
Can Bitpay handle the volume of transactions coming from a big company like Amazon? {If you add it to what they currently have on their books}
Last I have seen, they posted that the biggest single transactions they processed, was for $ 1 000 000... but that was a while ago, things might have grown since.
