Back when I used to be able to do BRU-BMA on regular scheduled flights, the customs folks were sometimes there by baggage claim but rarely flagged anyone for searches from any flights. This was when the then-pony-tail guy (Anders B) was finance minister for Reinfeldt. I don’t recall if they had Tull or Polis uniforms on each occasion, so maybe it was the police and not customs sometimes but there was definitely a customs declaration/control capability at Bromma that was being used sometimes times even for the regular scheduled commercial flights then.