Like everything over the past three months it is about most people following principles and doing their best to comply and the 80/20% rule will apply. I guess those that will try to congregate in numbers and think the rules shouldn't apply to them will already be doing that at home, and I'm not sure they are going to get much out of the new pub experience so will quickly switch back to ignoring social distancing rules in their own homes.
The bars have been shut down again in Texas. Bar owners are angry, but they didn't control their bars. The TABC (Texas Alcoholic Beverage Commission) had undercover officers checking out bars for compliance with rules that bar owners promised they would obey and enforce. Plus, the biggest error bar owners made is that they forgot that young people put EVERYTHING they do on the internet, including phone-video of them getting drunk and breaking all the rules in bars.
BTW, the use of the word "landlord" for what I assume is a pub owner/operator in the UK, is another case of words having very different meanings and usage in the US.

CD