Poorly written article, from what I can glean, it may have been the welts on the arm that triggered the arrest and charges. Arkansas is pretty lenient on corporal punishment. She should have aimed at the buttocks, though the girl may have been squirming away.
I never had a switch used on me, however my dad had a nice selection of belts for when I got out of line.
I had a switch used on me many times. Had stripes on the legs from it. Boy did they sting and yes they left little welts.