Bassets Pole A38 Southbound

Coming from Lichfield to Birmingham, why is it signed M42 South and M5 South going straight on at the big roundabout ?
But the better route is turning left by McDonalds .
Another issue is joining the M5 Southbound from the M42, if you are lane one in the average speed roadworks on the M5, there is no warning to move out of that lane by the concrete barrier.
I have seen many near misses, as the distance is very short .