I can’t say I believe some parts of that chart. The states I’m most familiar with, MS, TN, and AL, show that among the three MS has a higher sales tax than the other two. From personal experience that’s wildly incorrect, sales tax in parts of TN and AL will top 10% in certain areas since they both allow local taxes to be added on. MS has a 7% sales tax with a local option for an extra 2% but most areas don’t have that. That chart doesn’t look like it includes the local part of the sales tax, but I don’t care who I’m paying it to, just that I have to pay it. TN and AL as a rule have much higher sales taxes than MS.
The % shown isn’t the actual sales tax rate. It’s the % of the average person’s income that goes to pay sales taxes. MS shows a higher % than the other two because the average income in that state is so low.