Seriously, where are you eating? Nothing remotely resembling "high end" anywhere near me uses plastic furniture. It's all well-padded wood. From steak restaurants to ramen to pizza, I can't name a single place I go to that's plastic other than the typical fast food joints.
Some of the gastropub places near me have bare wooden seating. It's part of their "charm" this thread is swooning about. It's literally just a wooden picnic table, but yeah, that's so worth that extra money.
What about those "sit down" places where you load up a QR code, order from that site, pay from that site, but have a server bring your food? are they still a "sit down" place?
To me "sit down" implies you are seated by a host and waited on.
You may be overthinking this way too hard. It’s simply the level of service being received. There are some definite shades of gray here but throwing qr codes into the mix is pedantic. You could have fast food QR code ordering, fast casual and even sit down experiences. The QR code does not really factor too much into it.
I empathize with the economic predicament of restauranteurs but I'll continue to frequent establishments with better comfort features especially because the prices are high no matter where you go. Why pay $25 rushed sloppy meal when you could pay $30 for a better meal, in a better setting, and resulting in a better (earned!) tip.