Why is a downwind wind speed given in wind checks for aircraft on final?
'Downwind' speed does indeed mean that the aircraft will be landing with a slight tailwind. Each aircraft/airline has a maximum downwind component which is acceptable to land with - generally about 5-10 knots. From my experiences as a private pilot in Australia, I have observed that ATC will tell the flight crew the current downwind component without being requested to do so. I find that they will also advise if the crosswind component is more than about 5-10 knots. It has been a few months since I last heard it but I believe the wording is along the lines of "Qantas 32 heavy, wind 210 at 7, maximum downwind 7 knots, runway 01 cleared to land". This information is also available on the ATIS.