The vast majority of tickets sold are by season ticket, though. And, in that respect, Spurs are ridiculously more expensive. Cheapest £800, of which there are few, going all the way up to over £2000. Only 19 PL games included for the price.
I think people often overstate London weighting, too. Sure, Londoners earn more than those in other parts of the country. But their basic cost of living is also more - especially with regard to mortgages or rent. So, in terms of disposable income, Londoners are little, if at all, better off when it comes to paying for 'luxury' items such as football tickets. Should also be remembered that Londoners' average wage figure is warped by the significant number of super high earners working in the city (and the City).
None of which is to dismiss your point about about how expensive City games are too. I wouldn't dream of dissing City fans for their attendances. 30K plus average in the third tier back in your dark days immunises City fans from any derision in that respect. Proper fans.