i personally never use it in through out my life therefore i cannot say anything about this, but i think it may be using for shopping in from online shops.
Bitpay is actually quite known for many merchants even big merchants are using bitpay to accept bitcoin so they are trusted for sure and many small to big merchants are using them. But i don't think ebay or amazon gonna consider bitpay to accept bitcoin actually they may not accept bitcoin for few more years in future.
i think yes that bitpay is one of the know forum for online shopping and the big traders and merchants are using it for trading and shopping online. as it is one of the most trusted way of only trading.