My understanding is that there are a variety of significant factors that disproportionately affect marginalized people that make it harder to vote.
Systemically, we're dealing with a population that has been systemically marginalized. They're disproportionately imprisoned (and therefore stripped of their rights to vote), disproportionately targeted for less opportunities to vote (less ballot boxes per person, longer lines, etc), and their cultures around voting disproportionately targeted and excluded (sunday voting exclusion).
Similarly, it's also a population that disproportionately cannot afford to leave during a workday, during work hours, to stand in line for several hours to vote. That disproportionately cannot afford to participate in civic engagement, due to being unable to monetarily afford the documentation and cognitively afford the brain space to ensure they're registered in time, remember the ever-changing rules around voting, know which candidates to vote for, etc.
And then, this very same population is fully aware that the people who are in power have put in place the very same systemic oppression that makes their lives more difficult, and the very same system of civic engagement has produced the system of their oppression. There's a significant amount of cynicism that comes with that.
Sounds plausible, but that doesn't make it true (or false). I'm sorry to say that liberals play games in this space, and I don't particularly trust these neat narratives. The overarching objection I have is that it casts black folks as helpless victims unable to change their own circumstances. I find it very hard to believe that making voting inconvenient, even terribly inconvenient, even to the extent that you describe, is enough to dissuade fully half of all black people to opt-out. And if you're right, I would argue that the black people themselves need to fix it. If I was part of an oppressed minority and there was a legal, peaceful way for me to have even a sliver of a chance of changing my people's circumstances, you'd have to keep me out of the voting booth with a gun in my face. (And yeah, at that point I'd say a real revolution is in order.)
The baseline is 60% voter participation. It makes sense that a marginalized group with significantly higher barriers has a 10% reduction in participation to me!
Systemically, we're dealing with a population that has been systemically marginalized. They're disproportionately imprisoned (and therefore stripped of their rights to vote), disproportionately targeted for less opportunities to vote (less ballot boxes per person, longer lines, etc), and their cultures around voting disproportionately targeted and excluded (sunday voting exclusion).
Similarly, it's also a population that disproportionately cannot afford to leave during a workday, during work hours, to stand in line for several hours to vote. That disproportionately cannot afford to participate in civic engagement, due to being unable to monetarily afford the documentation and cognitively afford the brain space to ensure they're registered in time, remember the ever-changing rules around voting, know which candidates to vote for, etc.
And then, this very same population is fully aware that the people who are in power have put in place the very same systemic oppression that makes their lives more difficult, and the very same system of civic engagement has produced the system of their oppression. There's a significant amount of cynicism that comes with that.