Why do some airports give the departure frequency in the clearance while others do not.

YVR seems to always include the freq, while YYC and YYZ do not.

All 3 have parallel runways with separate frequencies listed on the SID charts.

Cheers

Some SID charts make it obvious which frequency will be used.

At YVR I would think it originated from various nuances in the routes, combined with many foreign pilots who don't frequent the area to become accustomed to what frequency to use. It's just easier to have clearance assign it than to add more phraseology with the take off clearance.

Not sure why we don't, but we don't.

YYC
Departures off 35L, 17R, 29, 26 = 124.52
Departures off 35R, 17L, 08, 11 = 119.8

EXCEPTION: If you are departing off a runway not compliant with our ground sort . Most common example is you are going to the oil patch (AVROM or SAXOL) and ask for 35L for departure. We switch you to 35L if traffic permits, and your departure frequency should be 119.8 in this case, as if you were departing off the other runway.

More rarely is if you are going west and require the 14000 foot runway, you would receive 124.52 as your departure frequency, as if you were departing the other runway.

The second departure controller in YYC is rarely opened, I've maybe seen it open three times in my five years here, in the tower yet the procedure is done.

NJ wrote:
The second departure controller in YYC is rarely opened, I've maybe seen it open three times in my five years here, in the tower yet the procedure is done.

You work a lot of evenings, then. Other than perhaps from 7-8:30 or 9 am, it's never been opened, but I can assure you it's used more often than you think. In the winter, with de-icing ops, the departures trickle out so departure never gets overloaded, but on a nice weather morning, you can sometimes overload departure (esp. if you throw in a few random VFR calls).

Edit: as you mentioned, the frequencies are determined geographically for organizational reasons (same as with arrival frequencies) for a couple of reasons: quick opening/closing of sectors and for when frequencies go kaput! (like they both did yesterday), it helps to isolate and figure out quickly who is on what freq rather than a free for all.