I had a cat, Pixie, who did this ..... Forever coming home without her collar.
Then one day my neighbours post was delivered to me by mistake. When I popped round to their house to deliver it, there was Pixie asleep on a cushion THAT THEY HAD BOUGHT SPECIALLY FOR HER .... and on the shelf was a little pile of collars!!!!
They used to take the collars off as they didnt like the jingling noise the bell and name tag made!!
The two neighbours were two very elderly maiden-lady sisters. I had a gentle word about the collars - explaining the need for Pixie to be identifiable as she was a cat who had a cat-flap and came and went.
We ended up with a special collar, with no bell, and an engraved plate on it (which the paid for!) with her details. Pixie used to go out in the morning and head straight for their house, then come back in the evening for "tea" and stay overnight with us. Funny little cat
I didnt have the heart to make too much fuss, as they clearly adored her, and she them.