I believe you are missing a substantial scalability issue. From an article in The Telegraph "the Globe has played to 480,000 people this year". It seems to seat somewhere around 2000, so I am willing to believe that they have about 200 performances per year.
Living in the US I'm well aware of urban sprawl and the near inability to define imaginary borders. However for the sake of argument, wikipedia claims a bit over 8 million inhabitants in London.
Some long division and making the HUGE assumption that The Globe only permits admittance to locals (LOL I'm guessing its probably 90% rich tourists like myself) then the average local can only visit The Globe once every 16 years rather than your "frequent trips". If my estimate of 90% tourist statistics is correct, then the average London resident can only physically visit The Globe once every 160 years. Of course the average lifespan of a london resident probably does not approach 160 years. And there are more cultural activities than just The Globe. But lets say you want to do something every weekend... Personally I'd take the train and live somewhere else, but if you can find 160*52 = 8352 other equally cheap and worthy cultural activities then it would scale.
"I would never have discovered my love for Classical music, ... if ... the tickets so cheap."
For me it was free audio rentals at the public library. Back when they used vinyl and magnetic tape. They freely loan CDs now, there is a limit but its ridiculous like 10 loaned at a time. I used to visit my local library every week, but the local symphony only plays something like 8 different performances per year, so do the math there. In this modern era its trendy to claim people only want someone elses streaming selections rather than having a mp3 of their own and making their own selection decisions, regardless of how ridiculous that is, its also more or less free.
I live on what amounts to a very small landed estate technically in the suburbs, but somewhat rural. I visit Chicago roughly annually and soak in some culture. I'm glad I don't live there, so I can trivially afford to visit, and my tourist dollars are crowding the locals out of the very cultural activities they supposedly pay $3000/month to live nearby, while I pay about a third that to live in a vastly superior location about 100 miles away. You'd be surprised what a couple extra thousand dollars per month adds up to in the long run.