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I live in Europe and perused of streetcar services in many cities with both narrow and wide streets. I've never in my entire life ever seen streetcars or light rail clogging traffic in any way. If OPs video speaks the truth regardless of libertarian bias, then it's either because the mentioned streetcar services are either not being given right of way or the line was poorly planned.
PS: I come from Lisbon, where despite tortuous geography, an excess of car traffic, and poor public transportation funding, streetcars are beloved by the population and seen as a reliable service.