Unfortunately, this is due to the fact that the media that is allowed into Syria is not allowed to travel with the Syrian side (the mainstream Western Media) and have embedded themselves with the "Free Army." In addition, western media seems to have "taken the side" of the rebels and are siding more with them as opposed to the Syrian government forces.
The main reason though is that the government is releasing limited information and the stories of civilian casualties at the hands of the government are more "sensational" and newsworthy in the minds of the media conglomerates.
There are some stories, such as this one, that are reported on from time to time but they are limited.
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