That's a really disappointing source. The headline is '200,000 people a day fly without REAL-ID', which starts out quite interesting.
It then goes on to explain that the TSA has reported 93% of traveler's complied with REAL ID, citing a TSA blog from a week prior which in fact states the same.
They then take this and couple it with a single day, which they state was the busiest travel day of the Memorial Day weekend, and extrapolate that 7% of the travelers that day must've failed to provide a REAL ID.
For the sake of conversation, this is a reasonable statement. Going back and using it to suggest 200k fly without it on a typical day is not reasonable, nor is your suggestion that a 6 months later it's still at 7% (or even typical travel volume hasn't changed.) There has to be better data available.
I was curious about this, so I looked up travel volume. YTD the daily average is 2,130,136 passengers. At 7%, this is 149,109.5 passengers or $2.449 B a year in fees. This ignores that you only pay the fee once very 10 days and assumes that all travelers pay the fee on every occurrence.
The number you came up with is still in the same order of magnitude of the source...