Why you can't tell a tea by it's colour?

I have a couple of tea strainer/infusers that I use to brew whole leaf tea. I recently spent part of a lunch hour searching for one that which would be slim enough to fit inside my REI travel mug. I discovered the Luci Loose Tea Infuser which is just narrow enough to fit inside the mug and looks like a gnome is sitting inside the mug. While at the tea store I decided to buy some British tea which is hard to find Earl Grey -- Taylors of Harrogate." Once back at the office it was time to test the new infuser and tea. I loaded up the infuser with tea and put milk in my mug and waited for the kettle to boil. The infuser sat in the mug steeping for four minutes and the tea looked white. I like my tea to have a bit of a brown color. I opened up the infuser and poured in another teaspoon of tea and waited. The tea still looked white. I was getting a little desperate so I grabbed a tea bag and plopped it into the mug and now I have brown tea. It was a highly caffeinated brew and much stronger than I'm use to. The moral of the story is just because your tea has a neutral colour after brewing doesn't mean it won't have a punch of caffeine.