I'd only be willing to reward companies that take bitcoin as a payment option if they offer appropriate discounts to make it worth my while. If they aren't willing to help incentivize more people to want to pay with bitcoin by offering these discounts then they deserve their fiat or less business in my mind.
I agree with the above two comments. Their savings aren't really enough that they can afford to pass them on to their customers but maybe over time they could if more people choose to use bitcoin. At the moment though I think we should just be happy that we can even spend our coins there at all. Some companies do offer a discount or other promotions for using bitcoin though like this
https://www.cannabis-seeds-bank.co.uk/cannabis-seeds-news/new-humboldt-strains10off-bitcoin-promo/