The world is a busy place and there is plenty of noise pollution. There are very few places people can go to find a bit of peace and quiet. A church is one of the places left in civilization where quiet is to be found. It is one of the few places open during the day that is often empty. This does not include Sunday or during special gatherings. Many churches are open during the daytime hours. It is perfectly acceptable to go in, take a seat and enjoy the quiet and solitude.
Older churches were often built of stone. The thick walls block out the noise of modern civilization. Churches are often surrounded by land as well. Distance from the road is a factor in maintaining the quiet within the church. These two factors make churches a perfect place to find the quiet and solitude some people may need.