Unfortunately most HR departments I’ve encountered are not set up to notify unsuccessful applicants. You should not assume that HR will let you know the outcome of your application no matter what they promise you or tell you. Not to excuse dishonesty but most recruiters are overworked and underpaid and recruiting isn’t always receiving the heaviest of investment from the company. It would be better, IMHO, to simply let applicants know they will only hear about a successful application, but that simply isn’t they way things are done.
I’ve had about 12 interviews in the past year and I’ve received one offer and in one case the recruiter notified me that I was unsuccessful. In every other case I just assumed I was unsuccessful because I never heard anything.
It can be very frustrating to put in all the effort for an interview and then play the waiting game, but you aren’t increasing your odds by bothering anyone. The best thing you can do is put in your best effort and then ramp up your efforts applying for other jobs.