Say 98% of white people and 97% of black people have access to the required kind of IDs... well even just a small difference would knock 1% of black voters out. It's very calculated
It's the same reason why some large urban areas have one or two polling stations with huge lines where you essentially have to wait all day to vote, while rural areas have way more places where you can be in and out very quickly
All calculate to reduce as much as possible the people who are more likely to vote democrat. It's not like it's a secret
It's not a secret to the point that in my state the GOP has actually been open about it with the reasoning of "So what we're just trying to win is that so bad???" ---