French portions aren't smaller - what they are is an appropriate size for 1 person.

Right, as long as that person is a jockey trying to make weight before a race.

Gariem:
Apparently no one is listening to you state price is not an issue and that you are light eaters in the evening. France (southern) and Italy are well known for small breakfast(breads and juice/coffee). The main meal is lunch. Do not be surprised to see Europeans eating what looks like USA dinners for lunch. Then they tend to eat lighter meals for dinner as a normal daily routine. Which may explain why statistically they are not as overweight as Americans given the fact that their main meal calories are burned during the day instead of before they go to bed. But then again, with the nightlife there I haven't quite figured out when they sleep.

You don't stipulate what you mean by 'finer' restaurants - I'm assuming you mean the most formal of restaurants, the kind with a sommelier as well as a maitre d', etc etc. At some formal restaurants at which we've eaten, the menu features some form of obligatory prix fixe, which lets one know from the start the policies of the restaurant. Other times, we have made inquiries at the time of booking. This also goes for when we want to have a light meal at semi-formal, more moderate places.

Regardless of their answer to our inquiries, it has always been made politely. Had it been made impolitely, say, accompanied with presumptuous and impertinent observations of what should or should not be affordable, what is or is not good etiquette, etc. etc., you can bet we would not think of that restaurant as 'fine', no matter how inflated their prices.

I was recently in a nice small restaurant in Paris where the clientele was mostly French but with a smattering of other nationalities.
Suddenly there was a lot of noise and confusion at the door. An American party was "making an entrance".
There was instant European solidarity as looks were exchanged and eyebrows raised.
Please, could you do us all a favour. Come in quietly, look at the menu, choose your meal and eat it slowly and with appreciation. After each course, relax and let your body language signal that you are letting it "go down".
Take at least two hours over your meal and don't gobble it down as though you are inhaling it.
Just accept what the restaurant has to offer and don't try to make your presence felt by having waiters dashing about bringing you extra plates.
Phew, I needed that!
Of course, I don't need to say that there are many Americans who are extremely civilised. As we always say, you don't notice those ones.

Well, Oldie, has your mother-in-law come for Christmas?

On this thing about Americans being speed-eaters, I'm forced to agree with you.
Have you seen Miriam Margolyes on TV retracing Dickens' footsteps in America?
I hope that it crosses the Pond because I think that our Canadian and United Statesfolk friends would enjoy it.
It made me re-read "American Notes".
Dickens makes the same point.

Oldie

"choose your meal and eat it slowly with appreciation..."

Would that be a dry or semi-dry appreciation?

"relax and let your body language signal that you are letting it go down..."

Please do not fart in restaurants, unless you are sitting near an open window...

"just accept what the restaurant has to offer"

Indeed. If the restaurant offers its patrons the option of, say, split portions, accept their prerogative to satisfy such requests (and such customers) as they wish, stop interfering with their judgment, and concentrate on finishing your peas, they're good for you.