Air travel has certainly become cheaper than it was in the past, but there are two sides to this - that credit card rewards are relatively high is largely a function of high credit card fees.
Thats true the fees are probably shared between all customers and businesses so its not fair for those who can’t get a credit card.
Right - the rewards system is essentially a wealth transfer to those who have access to credit with the rewards acting as a refund of the bulk of the fees.