No, it means they have to be prepared for it, possibly with face masks they can wear and epi-pens if necessary. How do they deal with walking down the street when there are dogs coming around a blind corner? Do you expect people to not ever own or walk dogs because people on the street might be allergic? Besides, most proper cabs have bullet proof glass between the front and back seat, so it's probably not really an issue anyway.
"In a
small number of cases, particularly among asthma sufferers,
there can be the risk of a severe asthma attack, and there
have been very occasional reports of the most severe, lifethreatening
form of allergy (anaphylaxis). "
"You may also be advised to use a preventer (steroid) inhaler and nasal spray
starting the day before any unavoidable exposure, for example a planned visit to a home where you know there
is a cat.
As stated above, if your doctor believes your symptoms could be very severe, you are likely to be prescribed
adrenaline (also known as epinephrine) The adrenaline injectors prescribed in the UK at present are
Emerade®, EpiPen® and Jext®."
What happens when multiple people have conflicting disabilities is not one with a well-settled answer, as far as I'm aware. It can create theoretical situations where all the available options potentially result in someone filing a lawsuit.
Well you can reasonably discriminate if the job requires it eg firefighters must be able to pass physical tests some jobs are barred to those with colour blindness for example