Kissing cousin to "oh, come on, you're not going to let a teensy little [xxxx] keep you home, are you?"
I think people aren't accustomed to people having "actually bad asthma" or diabetes and assume cos many people benefit from modern meds that it's not much of an issue. And they don't know stuff like people who use wheelchairs are at risk of UTIs and chest infections being VERY dangerous. I don't know how I do know stuff like this, possibly from my activism and work with disabled people, learning from people with different conditions and making sure I help educate others (or tell them to ask medical advice) in others (as I've met lifelong fairly severely disabled wheelchair users who didn't know a chest infection was potentially dangerous as all heck for them)
I often take great delight in asking ppl dismissing me where they got their medical degree (or equivalent clinical qualification) from and what specialism they have in snot/bones/etc and if they think their judgement is more important than my $clinician...
For all that clinicians are not all perfect, I rarely meet one who dismisses health/illness stuff for me, if anything they're inclined to slight overprotection and underestimating my capacity. Then again, there aren't many people a decade or more older than me with some of the conditions I was born with - they simply didn't survive. Older clinicians remember those patients and younger clinicians are better at recognising treatment doesn't always eradicate long term effects and issues.