That's just because tea drinking is currently socially acceptable. As examples, in a western context: what if it wasn't tea bags but used condoms? In a middle-eastern context: empty beer bottles?

Worse, you can't predict what will happen to society and its rules, up to the point of "normal" stuff becoming illegal. Take as an example the (new) laws on pornography in the UK. What if have an under-18s minor in your house and your trashbags are full of pornmags?