Discrimination is okay?

I came across a job ad a few days ago through my high school mailing list.
This is another thing that I think I have forgotten. How normal it is to put age, gender and marital status as limitation.
Urgently needed:
Yada yada yada...
Technical Support Staff and Supervisor with the following specification:

• Yada yada.. Bachelor of Science in Computer Science
• One year experience minimum in yada yada yada...
• yada yada...
• Hardworker, yada yada...
• Male, older than 25 years old, single (not married yet).
  

I mean,... no offense to the fellow high school friend who posted the ad. I'd imagine that this ad was just copied and pasted from his boss' instruction.
But,... whooaaa... if I were to find a job in Jakarta, and I have the qualification for all the bullet points, but not the last one, then I'm not eligible. Because, God forbid, I will have to get my sex changed to a man.
Isn't that what we call here in the US as the big D?

I remember one time, right after I finished my final project and getting ready to graduate, I actually did apply for a job which requested me to send them a passport-size picture of myself.
I think this kind of things are okay back home, huh?

Now that I look back, it really bothers me.
More over about that ad, which is looking only for single candidates.
Well, tough luck for dudes with rings, then.

I wish there is something to be done about this kind of things. But, I think there isn't.
Like another million things I'd love to see changed back home. I think I'll just have to drop the subject and move on with my life rather than frustrate myself.
I have a job now, and I love it. And I'm not planning to go back home. Well, unless something changes my destiny, then I might.
And if I ever go back & try to find a job. I will pass this kind of ads. Even if I qualified down to the last point.

I might, though, end up writing back to them just to ask: "Dear Sir / Madame, How come that this kind of discriminatory act can pass your judgment and went out to public? Tell me, why does the candidate have to be male, and over 25 year old, and single? Please send me back an answer because I'm itching with desire to send you back an argument for your argument. Sincerely unimpressed, Blue Cactus
P.S. FYI, I'm not interested in the job, with company policy like that, I'll pass. However, please do reply back to me regarding the above question."

And of course, I'll put my real name there.

Chances are, I won't get anything back from them.
But I hope, they'll be as bothered by my email as I am by the ad right now.