DRL show when a car is running
A big benefit is in a car park or along a row of parked cars - you can see which cars are running. Cyclists especially appreciate to know which car could drive off, but it helps everyone. Sweden has less fatalities per car, per mile and per population than the UK (at least according to wikipedia), so maybe it works. Both countries are among the safest in the wolrd btw.
A motorbike should occupy the same road space as a car (2/3 from the left of the lane ISTR from the test), so I don't buy this argument against DRL. If they are filtering unsafely, Darwin will rule.