Todays generation [and I mean the parents, not just the kids] has been bought up with an attitude of complacency, self-righteousness and enough ga’vah to ensure that mussar is totally ineffective. Where in the previous generations a rav could impose rules and regulations to ensure the Kedusha of his Kehilla wasn’t compromised, nowadays that would result in a mass Exodus from the Shul in question into a “breakaway minyan”, or worse – with the Kehilla totally ignoring and degrading the Rav. In todays day of multi-options, technology induced laziness and selfishness, nobody is going to change their way of life – or in this specific question, their mode of dress – just because you try force them to.
The age of the stick is over, for most practical purposes. Its time to introduce the carrot.
These same people who would oppose any takanos enforced by a Rav are people who are [somewhat] Y’rei Shamayim and Bnei Aliyah. They are people who do strive to do better in Avoidas Hashem. It’s not that they are bad people, they just react wrongly to external pressure. The trick is to motivate them.
Motivation doesn’t have to be in the form of prizes. That type of carrot would be almost useless to adults, and in the most case harmful to children who will be performing for the prizes instead of understanding whats right [TBD – difference between a reward and an incentive]. Motivation can be in a spiritual sense, or equally effectively, on an emotional level. You’ll notice that most of todays succesful “World Renowned Speakers” are not working with Mussar, they are working with Chizzuk.
The most catchy phenomena today is the group-segula-shtick. People are somehow much happier to undertake kabbalas in Avoidas Hashem for Bein Odom Lechaveiro than for Bein Odom Lamakom. It works. I’ve seen countless people improve in Shmiras Halashon, in Limmud Torah, in Tefilla etc. as a zchus for someone they know. Make a group text to forward to at least ten people, and everyone is in.
I know of a shul where talking during tefillah/krias haTorah was an issue for a while. The Rav tried dozens of times to put a stop to it, but to no avail. One week, a regular mispallel got up and emotionally asked of everyone to stop talking. He was childless for twenty years, and he asked that as a zechus for him, people should not talk in the Beis HaMedrash. From then, the shul was silent – and a year later, he had a beautiful baby girl.
No amount of letters or takanos can silence people who want to talk. You’ve got to aim at their hearts, and change what they want.