To be frank, I think that completely misses the point...
Of course only a small number of tourists are on the LH flights. The LH flights are targeted at Business Pax and Long-haul connections which it does really well. If you are a Tourist however looking for a city break on a modest-medium budget, BHX offers NOTHING for those passangers. They head up the M6, or down the M1 to get the cheaper flights.
Looking at Thursday 14th Dec, returning on Monday 18th , a great time for city breaks in Frankfurt to see the world famous German markets...
BHX - FRA (LH) = £314 Rtn
MAN - FRA (LH) = £258 Rtn
MAN - FRA (FR) = £80 Rtn
STN - FRA (FR) = £106 Rtn
LHR - FRA (BA) = £105 Rtn
With LH having their monopoly on their route, any tourists wishing to fly from BHX will end up paying £200 more than they to fly from Heathrow, or £235 more than they have to fly from Manchester...
Great for yields, awful for choice, competition and people who aren't business men. Is it any wonder that only 75% of the LH are direct travelers... I suspect none of them would want o travel from BHX at those prices!