Yeah it's weird. But there are t-shirts where it's understandable. For example, there's a t-shirt brand called wijld (in Europe), which:

- produce shirts in the EU and not in countries with child labor

- use 60%+ wood fibers for their shirts (which is more expensive, but ecologically better)

- feel great with high quality

So, while 30 bucks for a t-shirt seem expensive when you can get others for 5-10 bucks, they actually are better in many ways.

Of course, this isn't true for most expensive designer stuff ;)