It's possible there was a minimum purchase to get the sale price.
4 for $10 would imply you would be required to buy at least 4 to get the discount. While 2 for $5 would imply you only have to buy 2 to get the same discount.
Which is better? Buy 2 for $1? Or buy 1 for $1 and get the 2nd one...
Awww....you should've done some digging around here 1st. You could've saved some money by getting them here.
https://www.carparts.com/details/Ford/Ranger/Anzo/Tail_Light/2019/A1R311446.html
https://www.carparts.com/details/Ford/Ranger/Anzo/Tail_Light/2019/A1R311447.html