You're right each tx of BCH may cost less than what Bitcoin charged, but the main problem is that Bitcoin is much more widely accepted. People are also building a mindset if Bitcoin can also be used as an asset to hedging the inflation. Meanwhile, we have so many assets, which are also even more scalable than BCH.
So the key difference is that Bitcoin much more useful instead of BCH. Relying upon its scalability to push the adoption will never work because they days people can even use stable coin, which is not volatile as BCH to transacting anything.
The problem is that bitcoin is not used for main transaction and everyday payments, we have so many coins to use that and many chains that are cheap. Like these days look at how much USDT is moved via TRX and you will see that it's actually quite a lot, we use that a lot.
So we should be realizing that this is not something that we need to be worried about, I personally believe that this should be something that we do not really care about, we could be doing a lot better if we are careful. I understand bitcoin cash is still loved by certain group of people and that's fine, but the market has made it's decision and bitcoin cash is not used or liked that much by the market and gradually it's getting lower and lower on the rankings.