The church is the first place to spot the hats, even the bridesmaids have their own hair decoration to make this day unforgettable. But shhh.... this is the mass, be quiet and wait...
Each is unique, like the person who wears it of course, and it makes easy to find the one who wears it in a crowd (and we know that wedding crowds can be big). It is not rare that the color of the hat has been matched with the dress or with some other apparel, so you can imagine the time needed to compute these complicated adjustments. Whatever, the results are here in front of our eyes, and with the help of a couple of sparkling glasses (no, it would work even without), the charm and alchemy works...
Whoever invented this tradition was inspired and a wedding without hats would not be a real wedding, or at least would'nt deserve that we try our best for the best of all days. plus, don't forget that the groom and the bride often met at a previous wedding a few months before. And this particular hat on that particular face wasn't neutral that day. Is there a better reason to care for the hats?