I suspect that stuff tastes so vile, it has to be drunk with milk and sugar so as not to notice. In other words, what Camp Coffee was to coffee. In the late 1960s someone brought out a tea in freeze dried granules, complete with real citric acid ersatz lemon flavouring (as supplied to Soviet cosmonauts, who didn't really have much choice). For some reason, that never caught on.
When out and about I carry with me a little plastic mesh strainer that sits on the lip of my canteen mug, into which I put some real loose leaf tea (Like Toddy, I'm a Russian Caravan fan) and add boiling water. The leaves biodegrade on their own quicker than a used tea bag - what really is the problem?
Nick.