There are lots of cryptocurrency payment gateways. Each of them have different processing fees and transaction fees. some of them charge 1% to 5% fees on each transaction. which is a huge amount but merchants have to pay this amount. But there are payment gateways who charge the lowest amount like, one payment gateway only charges 0.23% processing fees on transaction. I find it very attractive because merchants will get more from it and it will be more beneficial for them eventually.
Transaction fees are not the only obstacle in adoption process. Nearly none of the business initiatives work directly with cryptocurrencies. They all need crypto-fiat transactions, so the problem with btc is that it's highly dependent on fiat banking services which provide this type of transfers.