I'm going to hazard a guess that they do not because that would mean an increase in the price and maybe lose a sale. It's such an easily purchased item that there would be little incentive to supply them or even make them available as an option.
Just my $.03.
Dick_B
2003 SunnyBrook 27FKS
2011 3/4 T Chevrolet Suburban
Equal-i-zer Hitch
One wife, two electric bikes (both Currie Tech Path+ models)