You’re in the UK, though, right? And aren’t most weddings in the daytime there? Evening is much more common here, at least in my community, so the black I’m talking about is party clothes. You’d see way less black in the US at a daytime wedding, too.
If there is a party at night, still no black?
Bear in mind that if you hold a wedding in the U.K, unless it’s in a very remote location the majority of the guests can probably set off from their homes in the morning and get home the same night. That means they have no hotel room to change in. So if you’re planning to have dancing and a party going on till late you’ll probably have the wedding ceremony in the early afternoon, dinner in the early evening, with dancing to follow. Whatever the guests turned up wearing, they wear till they go home.
This has been true of every wedding I've ever been to in the U.S.
The second bolded is true in my experience, too. But then, the weddings I've attended don't have a gap between the ceremony and the reception, with one pretty early in the daytime and one in the evening, as in the first bolded. Is that gap common in your experience (Iowa, NYC, or elsewhere)?