I90 TRACON Controller reported that another controller had to issue a traffic alert to an airliner on final approach due to a VFR aircraft that was operating directly below the Bravo; which happens all the time.

Narrative

I was working Final North; with a second Final Controller working Final South. We were west flow; widely spaced. The traffic was busy and steady; and the Final South Controller had a full final and downwind; with straight-in aircraft deviating around weather on their way towards the localizer. During the push; the other Final Controller; had to stop above his designated altitudes; and once had to issue a traffic alert to an airliner due to a VFR aircraft operating directly below the Bravo under our finals. The controller was very busy working a sequence and assigning speeds; and the VFR traffic added a dangerous level of complexity. Recommendation: Controllers at Houston TRACON have been asking for an airspace change for many years; and nothing ever happens. VFR aircraft fly directly under our finals all the time within 100 feet of the airlines on visual approaches. Having aircraft we're not talking to that close to our airliners is bad enough; but it also adds complexity to the busiest and most complex position in the building. We need the floor of the Bravo extended lower beneath our finals. We have close calls all the time and eventually our luck will run out.