How come greyhound buses have backward u.s. flags?

like in this picture a href="http://www.google.com/imgres?imgurl=http://blog.su-spectator.com/wp-content/uploads/2009/10/Greyhound-Bus.jpg&imgrefurl=http://boards.straightdope.com/sdmb/showthread.php%3Ft%3D174576&usg=__q1ToeAdV5dG5Bwz7RqRM6_jhMlI=&h=331&w=500&sz=126&hl=en&start=0&sig2=4nQsFjjcj7QL0R8AZ-hkdQ&zoom=1&tbnid=ITMcTp9QvWEeTM:&tbnh=117&tbnw=156&ei=mAIiToTAJKH50gHxgviYAw&prev=/search%3Fq%3Dgreyhound%2Bbus%2Bbackward%2Bflag%26um%3D1%26hl%3Den%26safe%3Doff%26biw%3D1429%26bih%3D677%26tbm%3Disch&um=1&itbs=1&iact=hc&vpx=160&vpy=88&dur=1516&hovh=183&hovw=276&tx=153&ty=80&page=1&ndsp=29&ved=1t:429,r:0,s:0" rel="nofollow"http://www.google.com/imgres?imgurl=http…/a