Why do only some of my photos taken on my phone get uploaded to photo stream on my mac

The Settings > Photo & Camera may be excluding photos from uploading - burst photos or HDR photos, so check the settings.

Also, the Photo Stream will only upload, if the Camera.app is closed, if you are connected to Wi-Fi, and if the battery charge is more than 20%.

See: Get help using My Photo Stream - Apple Support

Photos may also not upload, if you have exceeded upload limits: iCloud: Photo Stream limits

I really don't get it why apple doesn't allow photo stream to work under 3G/LTE. I have flat rate and I won't to have photos at home on apple TV while my wife is reading in front of ti, while I am playing with kids in the park.

While at that, why don't we have video stream too...

Sorry - only users just like you here - to talk to Apple (who knows "why" things) use the iphoto menu ==> provide iphoto feedback

LN