Possibly, although it would be a brave or stupid cyclist who'd go blithely zipping up the inside of an artic at traffic lights, trusting to the fact that there are three mirrors on the passenger side instead of two. The driver still has to look in them (and with the best will in the world, there are times when a driver is looking somewhere else - we've still got only two eyes), and all the mirrors in the world won't allow the driver to see through the corner of the trailer when the lorry is at an angle. Extra training may be helpful, however.