Seems the same elsewhere, too, as per other replies.

I recall our phones, as I said, having a card slot and coin slot at the end.

I wonder if they retrofitted, with the goal of getting people used to cards, before removing the change slot entirely. This logic seems typical here.

But then the smartphone explosion happened, so just decided to never buy new payphones with slots only.

EG, rather than phase out for card only, they'd have years of spare parts and phones, as they slowly removed booths.