You can use a co2 meter as a proxy. Outdoor levels are generally around 450 in a city. If your indoor space with open windows is there, you’re probably basically outside. If it is higher, you’re not.
See here for example, co2 is a commonly used tracer gas: https://www.ghdonline.org/uploads/Measuring_Air_Changes.pdf
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To be clear. I think very few restaurants have enough windows to really be like outside with a bunch of people in there.
I had a look at the greenhouses. Key difference from indoor dining: they prevent superspreader events. The problem with indoor dining is you have 30+ unmasked people dining in a poorly ventilated room. One infected person can infect many others.
In a two person tent an infected person can infect at most their dining partner, assuming waiters are provided good sanitary measures.
A CO2 meter can give a quick approximation of whether the greenhouse canopy spacs is more like an inside or outside.
My intuition was you’re right. But I could see it being the other way if it’s just a loose shield.