“Are there any hechshers that refuse to certify restaurants for that reason?”
I remember the Eda Hachredis in Jerusalem require all sit down eateries to close at a certain hour, due to preventing any hangouts and mingling etc. I recall they actually took off more than one Hechsher due to violating the above.
Anyways, my point was not about the above, it was just to refute the “tznius” concern when regarding Eruvin. The ones that are demanding those standards should demand it at all aspects – not only Eruvin.
In fact, I heard from many old time Lakewooder’s that there was a time when the first Pizza shop opened up, many Chushuva yidden refused to go in. And it was sort of an embarrassment to go in. Well, it’s something that most people today cannot even relate to comprehend, however, those were the standards of the Bnei Torah, at the time. People lived by the most simple life style and standards possible.