I can’t believe the OP’s post!! How disgraceful to the judges and everyone who showed up ready to perform. And mobiles in the ring?!! haha. Unbelievable.
In Ireland, the local and lower rated circuit jumpers can usually be expected to show up in tall boots, various shades of cream - brown breeches, a lighter coloured polo, and hair up or braided/bun. Pony kids of course have paddock boots and gaiters. And really, paddock boots and half chaps would be fine at that level. Higher rated and national level shows, then you’re in coat, show shirt, light tan or white breeches, gleaming boots and tack, hair done. You might not be marked on it, but seriously - there is a dress code for this sport! Revolving fashion choices - another story for another day.
For Hunter shows at any level, you’re expected to be wearing your hunter plaid coats, white shirt with four tie collar and pin, tan breeches, show cane, etc but in more performance hunters or classics, a dark coat, white shirt with stock collar (sometimes even pinned), light tan breeches, shiny shiny boots, ‘well controlled’ hair, and gleaming tack and horse is de rigeur.
I have longish hair but it is still easy enough to put up, and I wear it the same way every time I ride. My helmet is fitted to that. It was my understanding that your helmet should be fitted to how your head (and hair) is normally. For my trainer at least, lessons wear is minimum schooling show attire. It’s respectful, it shows you spend some time with your horse and tack, and if you are always in decent enough clothing, it’s not weird or restricting to suddenly have to wear long show shirts and jackets and tight boots. I usually train in a collared short sleeve or long-sleeve shirt that I don’t show in but is basically the same, tan breeches, same boots I would show in, etc. It’s just easier than buying tons of everything!