AIRBUS A319 CREW FLEW THROUGH THE LOC COURSE WHEN CLRED TO INTERCEPT AND TRACK INBOUND.

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FLEW BRADFORD 3 ARR TO ORD. AFTER BRADFORD; AT 11000 FT; VECTORED TO E. HAD BRIEFED RWY 9L ILS. AFTER CONSIDERABLE VECTORING; WE WERE TOLD TO EXPECT RWY 4R ILS. WHILE 61 DME S OF ORD; WE WERE TURNED TO N AND TOLD TO INTERCEPT RWY 4R LOC. WE WERE NOT TOLD HOW FAR WE WERE FROM THE LOC. I SELECTED THE 'LOC' BUTTON AND THE ACFT IMMEDIATELY TURNED R. SUSPECTING A FALSE LOCK-ON DUE TO THE DISTANCE TO ORD; I RETURNED TO 'HDG.' I HAD TO CHANGE FROM 40 NM TO 80 NM SCALE ON THE NAV DISPLAY (ELIMINATES TCASII INFO DISPLAY) TO 'SEE' ORD; BUT INTO WAS SO BUNCHED THAT WE COULD NOT VISUALIZE THE EXTENDED RWY 4R LOC. I HAD THE FO TYPE IN 'RAHNN' -- A BETTER VISUAL AND WE COULD SEE WE WERE THROUGH THE LOC. ORD APCH SAW THIS TOO AT THE SAME TIME AND GAVE US A 070 DEG TO INTERCEPT RWY 4R LOC. ON BOEING GLASS; IT IS EASY TO 'EXTEND THE CTRLINE.' THIS IS A LABOR INTENSIVE TASK ON AIRBUS GLASS. THE CTLR SHOULD HAVE TOLD US HOW FAR WE WERE FROM THE LOC COURSE. WHY CLR US 61 DME FROM ORD WHEN THE AERONAUTICAL INFO MANUAL SAYS A LOC IS USUALLY GOOD FOR ONLY 18 NM? JUST 5 DAYS EARLIER; I WAS CLRED TO INTERCEPT THE RWY 27 LOC AT SAN FROM 40 MI OUT. WE DID GET AN OBVIOUS FALSE LOCK-ON WHEN 'LOC' WAS SELECTED. THIS FALSE LOCK-ON BIASED ME AGAINST THE ORD RWY 4R LOC R TURN WHEN 'LOC' WAS SELECTED. ONCE VECTORED SO FAR OFF THE BRADFORD 3 ARR; WE SHOULD HAVE 'CLEANED UP THE BOX.' WITH A PROPERLY SEQUENCED BOX; 'NAV' WOULD BE A BETTER CHOICE THAN 'LOC' FOR INTERCEPTING A LOC FAR FROM AN ARPT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR THINKS THE AIRBUS FMC IS OVERLY COMPLEX AND HARD TO USE; COMPARED TO THE BOEING SYS. HIS EXAMPLE IS A WAYPOINT EXTENSION. IT IS A 10-12 KEYSTROKE PROC TO EXTEND IN THE AIRBUS; WHEREAS ONLY A 2 KEYSTROKE PROC IN THE BOEING. HE THINKS AIRBUS SHOULD BE REQUIRED TO MAKE THEIR SYS MORE USER FRIENDLY. THE RPTR ALSO THINKS THAT THE ATC SYS SHOULD NOT CLR ACFT TO TRACK THE LOC; WHEN OUT OF RANGE.