In some ways, I don't think Kayak/Expedia/etc. want to show you the full fare either. They want to show you a price you'll pay. Too bad for you if your flight ends up costing considerably more.
I think JetStar is the worst offender http://www.jetstar.com/au/en/planning-and-booking/baggage/ch... $160/bag if you don't add the bag to your ticket at time of booking (and as an international traveller, you won't know to do this). I had to pay $120 for a bag on a $80 ticket.
I've also been charged extra for a seat by WestJet, not advanced seating, not a special seat, just sold me a ticket that didn't include a seat, and of course, you're not allowed to stand.
Outside of baggage, cancellation and seat selection fees, in Canada we also have 'fuel surcharge' fees, as if your ticket is worth anything if the airline didn't have fuel.
The whole industry is becoming a nickel-and-dime racket. What are the chances somebody will step in and require all tickets to show a final price (with the exception of change fees, which are understandable).