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.
Yes, in that case it’s pretty misleading even though it might technically be true. One would look at that and assume that Alabama’s taxes were lower than MS but I know from experience that’s not the case. Alabama’s sales taxes are so high that I avoid purchasing things when I pass through the state. In addition to the state sales they also add county and city, and if you’re in a tourist area they add another tourism sales tax. I stopped at Bass Pro Shops in Spanish Fort AL once and if I remember right the sales tax was around 13%, I made a quip to the store manager asking if Barack Obama was their store manager and he didn’t smile.