Earlier quoted context omitted.
There are transaction fees with some cryptocurrencies (for example Bitcoin) – for a small purchase they can be much more than 2%.
Fees are always optional. Right now $0.25 will make a tx confirm in under 70 minutes (typical 225-byte tx, 40 sat/B: https://bitcoinfees.21.co ). Solutions are being developed left & right to further reduce this: alts, segwit, block size increases (segwit2x, BCH 8MB blocks), payment channels, etc. (Answer edited. Yes merchants care indirectly about fees.)
As a merchant I absolutely disagree: the cost of my product is how much it costs the user, which includes the complete costs to the user, not just my price.