I think they all do it. But not sure if it's an on-purpose (realtors do it here as well for homes), or lack of staffing to remember to pull the ads. Judi Koz had done it as well years ago when I was looking. Would inquire about the listing, only to be told it was either sold or under contract. Would see the same listings days, weeks and months later.
On the one hand, I can see if they're hedging bets (just because something's under contract doesn't mean something wont' happen and things will fall apart at the last minute, so then you can have a backup or something).
But, I have problems when you tell the broker that the listing is still active (especially if it's sold) and weeks/months later it's still there. THAT, IMO is either lazy or bait and switch (oh, that's not for sale, but I have this other more expensive one for you).