There is a big problem: the infrastructure needed for good public transport is increasingly nontrivial, especially in the larger European cities, which tend to be older cities with historic centres which they wish to preserve. It's all well and good to build a city from the ground up in a way that's PT friendly, but if you have a channel city, or one with a densely populated and vitised historic centre, it's immensely hard to be able to have a well-regulated and up to snuff public transport.

Some anecdota: the netherlands has an excellent public transport networks. Our busiest train station, Utrecht Central station, has over a hundred million passengers going through it each year. To put that into perspective: there are roughly 17 million people in the Netherlands. To put that into further perspective: utrecht has 330K inhabitants. Over 5 times the entire population of the entire country is going through that station each year, and over three hundred times the entire population of the city the train station is in. I'm stunned daily by how little delays we have.

However: the Uithof, the (mostly) STEM part of the Utrecht University's campus, is pretty big by Dutch standards. Most of them use the public transport to get there. There are roughly 35K people using public transport to travel to the Uithof each day, with an estimated 45K in 2020. There are a little over 2 double-bendy busses going to the Uithof from the Central station each minute during rush hour. Each double-bendy bus can, according to the specs [1], carry 150 people. A friend of mine who still goes to the Uithof daily using these busses told me that if he has to get there during rush hour, or leave during rush hour, will often have to wait anywhere from 30 to 45 minutes until there's space for him on a bus.

To combat this, the goverment is spending 440 million euros to build a tram line from Central station to the Uithof, and it's still not sure that this will be enough.

1: http://soderholmbus.com/abc/pdfs/AGG300.pdf