Telecom, etc. are far, far more harmful IMHO
Yet even under this situation of "competition" between say a cable company and a phone company in most regions you have a duopoly and in very rare cases you find tripolies in the US. I did accuse these companies of swapping agreements in a friendly matter like if not exactly as a Trust to evenly distribute such duopolies and make it tough to enforce the places where the laissez faire regulatory environment around the duopolies have led to de facto monopolies by benchmarks such as which provide modern internet speeds at the neighborhood and/or building level. (It's been too long since the US was last interested in trust busting. It's also maybe been too long with the hand off the regulatory rudder for those cable and phone monopoly licenses.)
That's a weird way of phrasing it. Cable companies own their lines because they paid to build them. But they haven't been "intentionally granted monopolies" as you claimed above, because another provider could come in and build lines and provide service. (Power companies, by contrast, generally do have a monopoly in that sense.)
This has always been called a "natural monopoly": https://en.wikipedia.org/wiki/Natural_monopoly
Most regions are aware that cable and/or phone lines form a natural monopoly, and thus intentionally granted that monopoly, placing regulatory bodies just as they did power, water, etc.
Just look at how badly Google Fiber is failing some cities to see how hard it is for "another provider could come in and build lines and provide service". It may be "slightly" easier to have competing cable providers than competing power companies (though keep in mind early America did have more competing power companies in some regions), but it's not that much easier, it's still a natural monopoly.
In every state I've ever lived, for example, Comcast is the only company that provides acceptable internet speeds. DSL and satellite providers don't even come close enough to count as competition. So Comcast has the localized monopoly on the infrastructure necessary to actually provide a good product.
Not arguing that starting a telecom is easier than a search engine, but I think a large part of that difficulty is inherent to the industry.
I think the overall point though is that both the telecom and search engine market experience the network effect. In a telecom's case, the effect is more literal. For search engines, they increase in value as they can collect data on more and more users (which increases the value of the search engine to the users and the cycle continues). Saying that there are dozens of alternatives to me is like saying there are dozens of alternatives to Facebook. There are, but my Grandma isn't on them so do I really care?
I think that the network effect is really hard to regulate around effectively. Just look at Bell. the resulting companies from the Bell antitrust case are the same companies we are discussing as having monopolies on internet access. I absolutely agree that we have an issue, but I just don't know of a solution.