You must be extremely attractive. I've had girls do this before and it really comes off like they don't care about me. Either that or maybe it's just different where I live. I always expect some kind of confirmation, like message me the day of just so I know you didn't make other plans. I actually had one girl that planned to go out for drinks on Sunday, weeks in advance. And then went quiet the day of. Kinda figured what was up, I asked just to make sure, and of course it turns out she made plans with someone else. Since then I just come to expect if she goes quiet, she's not interested and I need to find someone that actually is interested.