As a hiring manager in a large company, I can tell you that most of the people you are interviewing with aren't being actively rude, they are overwhelmed.
If I took the time to contact all the people I passed on to give them an explanation, it would consume more time than I can afford. The people making the decision to hire are - usually - the ones with the most to do.
The safest bet is to consider any lack of communication a "no." Personally, if I want to hire someone, I make the offer on the same day I interview them. Any company worth your time should do the same.
On a side note, you should make a habit of giving and getting business cards from your interviewers - particularly the decision maker. Also, turn the interview around if you can. Your talents are worth a good company. Make THEM SELL YOU on their job. Don't take a stance of hope. Make sure they leave the interview knowing you are the right person, and the question is "will YOU accept their offer?"
First, do a phone screen, not more than 1/2 hour of questions around the tech, team fit, and motivations. Involve a few people from the team the person will work with. This phone screen should weed out 80-90% of candidates. If you have a doubt about them on the phone, that's a no.
If they pass the phone interview, invite them back and tell them to be prepared to code during the interview.
Start your actual interview with code test like FizzBuzz or something similar. Have them do this in front of you and one or two other competent developers. Many candidates will outright fail this type of test. If they do, politely end the process there.
The rest of the interview should be a few panel type interviews with the team and both technical and team fit questions. Include non developers if you can (testers, marketing, ops, etc.). Leave empty spaces in the conversation for the candidate to fill. They more they talk the more they will reveal. If you start getting a preponderance of thumbs down, politely end the process immediately. Don't waste time.
Take everyone's feedback seriously, and arrange to get it quickly from everyone. Preferably you would have a thumbs up/thumbs down from everyone immediately. (Know your team well enough to know who gives only thumbs down...) Look for and pay attention to biases within the group. As the manager, sometimes you have to make a call that the team might not like. Be prepared and courageous enough to do so. (For instance, hiring a process-oriented qualified woman candidate might not sit well with your team of male cowboy coders, but it might make the team better...)
Typically, if the candidate has gotten this far, then I take them and the team to lunch to get them in a more informal setting. As long as the candidate doesn't say something stupid or otherwise fall on their face during lunch, I'm ready to hire them.
If you are in the position to do so, have the offer ready, and make the offer right then and there. If you find the right person, ACT. Cancel remaining interviews with your apologies.
If I took the time to contact all the people I passed on to give them an explanation, it would consume more time than I can afford. The people making the decision to hire are - usually - the ones with the most to do.
The safest bet is to consider any lack of communication a "no." Personally, if I want to hire someone, I make the offer on the same day I interview them. Any company worth your time should do the same.
On a side note, you should make a habit of giving and getting business cards from your interviewers - particularly the decision maker. Also, turn the interview around if you can. Your talents are worth a good company. Make THEM SELL YOU on their job. Don't take a stance of hope. Make sure they leave the interview knowing you are the right person, and the question is "will YOU accept their offer?"
Good luck!