A quick thought.
Why should the principal worship service be on a Sunday, particularly late Sunday morning? There are reasonable arguments for Christians, as it commemorates Christ’s resurrection. But that argues for a weekly sunrise service, and — let me tell you — if that were an option, I’d gladly take it. I don’t have to get up to milk the cows then walk miles to the chapel. The customary 11 a.m. service breaks up one of my day’s off. But I’ll gladly do it. Others won’t.
And for Unitarian Universalists, most of whom aren’t Christian, the remaining reasons are customary or cultural.
For new churches, who (1) have to appeal to people to take time to meet and (2) need to find a place to meet, Sunday morning must be the worst time, particularly since some of space best suited for worship are churches, and these are occupied then.
As I said, quick thought.