Why can't hirers just let us know their decision?

I mean, so far I have applied for over 30+ applications and none of them have bothered to respond or move to the next step. To say one, 2 months ago I have applied to a Team Lead Intern position at Amazon and have done the online assessment test. After that, there's no response. I keep waiting that they'll respond one day but it seems never. If they feel that I'm not suitable for the role I applied, why can't they just send a mail telling me that