Why is Buddhism less evangelical than Christianity?

Currently when I walk to work I frequently pass Christians of various denominations passing out free books and talking to passers by. I have never heard of a Buddhist group doing the same. I think it is a common perception that Buddhism is not an evangelical religion and Christianity most definitely is. I think this one of the reasons is why people (in the UK) are generally fairly well disposed to Buddhists. But are my perceptions correct? Is Buddhism really not an evangelical religion? It is a universal religion like Christianity and in both there are notions of personal salvation (liberation/nirvana) that surely everyone would benefit from. Is there something in the scriptures or teachings that make Buddhist less evangelical? Or is it just something cultural and in a different place and time things might look very different? Or am I just flat wrong and Buddhism wants to spread the word just as much as Christianity but I'm just not seeing it.