The logistics of certain hiring practices may be themselves biased in terms of age (or other factors), which is questionably ethical. This trial week seems to discriminate against those who cannot trivially sacrifice vacation time (employees with families, for example). There are others, too; I've heard other founders scheduling interviews with candidates late into the evening or night, even on weekends. With kids to tend to, that would be an incredibly frustrating situation.
Nothing is quite so black and white that these acts are themselves evil, but I do hope companies aren't becoming culturally biased. If you're flexible with your policies, then perhaps you'll do fine. With that said, there's something to be said to sticking to some conventions in the interest of not alienating candidates