I was under the impression that it didn't in the early days in the US. For sure, in several other countries, it started without ads, and some channels stayed ad

I was under the impression that it didn't in the early days in the US. For sure, in several other countries, it started without ads, and some channels stayed ad-free whereas others did get ads and getting more of them (though, nothing quite as horrible as what the US has these days -- on a recent visit to New York, my kids tried to watch Cartoon Network on the Hotel Television, and it was probably 30% ads -- never seen anything remotely close to that in UK, Germany and other countries I visit)