House of Cards season 3 release policy

That is an interesting question. First of all, yes, the episodes are all released at the same time and it has always been that way for House of Cards.

The main point to consider here is, that House of Cards is actually produced explicitly by and for an online streaming service (and is to my knowledge the first major example of that). This means it did not air on TV first and there was no technical/practical necessity to release it as weekly/daily episodes, since Netflix is not bound to a specific time slot on a TV channel. So there is no real need and nothing to be gained from releasing the episodes in a serial fashion¹

Now by doing so, they can actually allow people to adapt their ways of consumptions to their own preferences. It is largely due to the advent of streaming services that nowadays the so-called binge-watching is getting more and more popular. And by releasing all at once, they not only can cater to people enjoying that way of watching, even more so they can explicitly play this out as a difference and advantage compared to "traditional" television. But people prefering the good old weekly episodes can still schedule it that way themselves. So they give their clients a more flexible way to view their stuff and can thus only win more possible viewers.

1) _{One could argue that they could release espisodes monthly, to bind their viewers to renew their subscription each month, but I'd surmise such a strategy and stretched release would not be very welcomed by their clients.}

All three seasons of House of Cards have been released this way.

Season 1 was released February 1st, 2013

Season 2 was released February 14th, 2014

Season 3 was released February 27th, 2015

I don't know why Netflix does this... probably because they can.

Shows like the ones you mention, Castle & 24, are Network shows. They air on broadcast TV at particular times and are released with ads, about one episode per week. If they released the episodes at the beginning of the season, why would anyone come back every week to watch the episodes (and the ads)? They wouldn't.

Netflix isn't ad-based and there's no benefit to them to slow-release shows... instead, they get a huge burst of viewership and a big news splash by releasing full seasons and people can binge-watch to their heart's content.