Who are Google’s serious competitors? Sure there are other search engines but I’d argue that none are serious or even marginal threats.
People will tolerate sub-optimal experiences if they perceive they don’t have any option; just ask anyone who has stood in line at the DMV.
The first sign of a monopoly is a rapid performance degradation which can’t be explained by economics of scale and which did not exist in prior versions of a product. Free market forces and incentive structures no longer apply to monopolies, which is why many large corporations can get away with sloppy work and treating their customers poorly, but do not see much if any consequences. Behavior that would have been disastrous in a startup is tolerable in a large corporation operating as a monopoly.
A product owner or dev at Google would be committing career suicide if they started to care about performance at this point, because that would not result in any appreciable changes or outcomes consistent with the incentive structures at Google.