Most likely because they are not used to hearing them. For people who have lived there for awhile, grew up there, they are a part of daily life, are expected and many probably set their watches by the bells. It's like people who move out into the country and then complain because there is farm equipment being driven on the roads or wildlife in their yards. After awhile they will get used to it and won't be bothered by the bells.
I wish we had bells here instead of a lot of trains with load horns.
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