As far as I understood, BRS is mandatory for EASA registered microlights. Thene there are the Cirrus fractions and the retrofitted ones - these usually have the mentioned little stickers. At almost all certified old machines it should be easy to rescue people, as there are no BRS. The number of retrofitted Cessna for example is homeopathic.
Experimentals may be a problem, but I would assume they have the stickers.
As a fireman myself I can only report on our training session back when I was in Europe. There were only 3 or 4 manufacturers of BRS than, and we called them up for training material - which they provided to us to learn how to handle such blood things. Even one of them sent an instructor to give lessons for first steps before the bomb squat arrives to get rid of the BRS.