I've never knowingly had flu. The one time I thought I did, it turned out to be campylobacter, tested due to stubborn symptoms lingering on afterwards.
Unless I was seriously ill which I'm not currently statistically high risk of, there's no point in me testing which brand of sniffle I have for minor illness, be it flu or covid. There is a point for some people where it opens up access to additional treatment, but if I'm too ill to function, I'll be in bed, if I can function on OTC remedies, my employer expects me to plough on.
I don't see the point for myself to be vaccinated as supplies are finite and there are people who need it more than me. I accepted the vaccine in pregnancy, and consent for my children to have it. If it was offered to me, I'd accept (but not covid as I did not react well to them and they were worse than the illness) but I'm not going to hunt around to access a provider when other people have greater need.
Depressingly when my class was called for their vaccinations, only 4 had consent from their parents, about 1:6.
I have certainly been exposed to flu this autumn. Significant numbers of staff and students have been off ill with it, and DS2 was ill for 10 days with very clear flu-like symptoms, and I was cuddling up with him. I recently had a week of feeling "under the weather" like I was fending something off (but not actually ill, just drained), but my role at work is more pressured the higher the absence rate is, so my bar for illness has to be pretty high.
For the majority of people, they'll never know exactly what "brand" of mild illness they have is and it makes no difference to their treatment and recovery, which is why the myth of "if you can't bend down for a £20 note" continues.
Where I do get twitchy since 2020 is the number of people that seem to think that the spread of all minor illness should be curtailed lest it become more serious in individuals, but 2020/21 demonstrated that the social and economic toll of that is too great and has enormous, lasting repercussions.