Ticket resellers would be far too small a market for Google to actually do anything nefarious. It's just not worth risking a precedent.
I think Google also knows these concerns very well. I'm absolutely sure that they have more lawyers than programmers working on the upcoming ad blocking.
Strategically, Google owns so much of the open internet that they get plenty of benefits by, for example, improving ad quality overall. Their competitors aren't some ticket resellers that they would screw over by banning their ads. It's Facebook, Apple, and possibly Amazon with closed ecosystems.
That's why Chrome is such an excellent browser: Google's interests are almost completely aligned with someone browsing the internet. That, plus their basically unlimited money, and what's probably the world's best software dev operation meant that they easily outclassed Firefox without really trying[0]. Chrome was started at a time where native apps (and the Facebook SDK) had become superior platforms for app development: Remember Zynga? Yeah, me neither...
[0]: The "Chrome" wave of browser advancement has probably hit a sort of natural slowdown for now, which is (among other things) what allowed Firefox to catch up.
It reminds me of a conversation here about Google's behavior with regards to their upcoming Ad Blocker. It would be very easy for Google to guide their business decisions in a certain way, then say "This is how things should be" and use their clout to force everyone to behave in that way, except that everyone else will then be playing catch-up. They have the power to do it, and in this case, it's for a good cause (plus, they're not a ticket reseller, etc).
But will that always be the case? Who decides which specific instance, if any, is "a bridge too far"? Is this something we even need to worry about, or should we let the market decide? Like I said, I'm curious to see how these kinds of actions by Google (and other market leaders) evolve over time.