Shabbat fences loss

Have a good week Rabbi,
On Shabbat, I happened to come across an avidah and wondered if it contained a prohibition. Do not ignore several aspects:

1. The loss (probably a bracelet belonging to a little girl) was of low value (say 20 shekels). I thought that a reasonable person would forgive the finder of the loss if he did not bother to return the loss, because it is a great deal of trouble in relation to the low value. In other words, I am here to argue that only starting from a significant value of, say, 100 shekels, do people expect the finder to bother with hanging signs and locating the owner for the purpose of return, and below that, it can be assumed that a reasonable person would forgive the finder and not expect him to bother with return, and therefore there is no obligation to return.
2. Even without consideration number 1, if I am strict about not shaking on Shabbat, even in a place with a mixture, does that exempt me from the obligation to make restitution on Shabbat?
3. Even without considerations 1+2, I noticed that nowadays the common custom of religious people (correct me if I’m wrong) is that they prefer to leave the lost item where it is, assuming that the owner of the lost item will return to the place and find it, and it is precisely bringing the lost item into your home that will harm the chances of recovery. Is this a correct consideration?

Best regards,