Why would they? I get that the majority of people are ignorant about anything they don't have direct experience with (and often still that stuff too), but even just thinking for 5 minutes about what the border agents do and their responsibilities should lead you to draw a blank on what use whips could have. Any utility possible through a whip is going to be easier and more efficiently done with some modern tool like pepper spray, a taser or handcuffs. They aren't cowboys trying to lasso some errant cattle, they're on horseback because it's still the most efficient mode of transport for the terrain they work in. The only way to believe they are out there whipping people is if you already think they're just evil and want to hurt others.
Why would they? I get that the majority of people are ignorant about anything they don't have direct experience with (and often still that stuff too), but even just thinking for 5 minutes about what the border agents do and their responsibilities should lead you to draw a blank on what use whips could have. Any utility possible through a whip is going to be easier and more efficiently done with some modern tool like pepper spray, a taser or handcuffs. They aren't cowboys trying to lasso some errant cattle, they're on horseback because it's still the most efficient mode of transport for the terrain they work in. The only way to believe they are out there whipping people is if you already think they're just evil and want to hurt others.