It might not be very eco-friendly, but when you’re out and about with babies and someone needs a change, disposable change mats are unbelievably useful.
The only ones I’ve seen, although there must be other similar ones, are made by Pampers and consist of a slightly padded absorbent upper layer with a waterproof underlay. Bigger than the average travel change mat they can be squished into any available space you have, and when you get to public change table (or car, park, wherever) you just shake it open, pop baby down, change and then throw it away with the dirty diaper.
The alternative is to use disinfectant wipes and wipe down the public change table; get out the (pretty small) change mat which came with your diaper bag, unfold it and try and keep baby on it; and then afterwards find antibacterial wipes again to wipe off said change mat and repack it in your bag, hoping that you haven’t missed anything that could cause your diaper bag to give off an interesting perfume.
For me, the disposable version wins every time, particularly when I have to change one baby while the other is getting worked up in the stroller nearby. I hope the environment will forgive me.