CB dealt with Gemplus to add chip to all new cards emitted since 1992 so we had them for a long time. I don't know how it spread over europe, but as we had the industrial capacity to provide chip cards to everyone and a free market, I think it was easy to sell that to lots of european banks. CHIP+PIN is a really great deal for banks : it's cheap and the responsibility of all payments made with the PIN is on the card owner and are really hard (or impossible) to dispute.
I've been to stores in the US where they just swipe your magstrip and hand you back the card. No signature, no pin, they don't even look at it, so you can basically clone cards like it's still 1985.
This is consistent with how my UK bank treats any transaction occurring in the US: usually it's an instant card block and a polite phone call from them to check that it was actually me.
Sounds like the other response about transaction fees is on the right track.
Even now you never have to pin in the US.