Why cant a person find out if there allergic to wasps sting until they have been stung once as surly thats dangerous if they are allergic??

Logical question: However that's not a routine or practical to test eveyone, may be people who ate at risk who work in areas where wasps/bees pose a threat, even though testing if positive wouldn't predict what happens on true exposure, as you still won't develop a reaction, and reactions differ in severity in different people or different ages. Better to have an epinephrine auto-injector & antihistamine handy