> that's still $8bn to collect $1bn

No.

> Or am I missing something?

Read the article and the CBO report [1].

$8bn produced this $1bn. It also produced other additional revenue. CBO projects $6.40 of new revenue for each dollar spent by the IRS.

[1] https://www.cbo.gov/publication/60037

Yeah, in the sense that my car cost $32k and I drove it to my job that made me $3k today. But I will drive the car tomorrow as well. And I drove it yesterday too.