In Seattle, a city with lots of trees, the big problem today is sanctioned tree killing. The current over-focus on building housing and increasing density has meant revised tree codes that are friendly to builders and reduced enforcement that ignores the obvious destruction of the city’s tree cover.
As an example: a friend living next to a new development saw the builders come cut down several large old trees in the evening on a weekend (probably to avoid attention), and immediately feed them into a large wood chipper towed on site. They were alerted to it by the sound of big trees crashing to the ground. It all happened very quickly. The city was involved due to complaints from multiple neighbors but they decided there was no evidence the trees were protected (due to size), which of course was by design since the evidence was immediately shredded and no one was quick enough to get a photo of the crime. In the end the city did find there was illegal clearing of many trees without appropriate permits (from old survey maps of the lot), but chose not to apply the code and fines (which can be big for large trees) and let the developer plant a small number of saplings in some other site (outside of the city) as if that were equivalent. What was especially concerning was the city told complaining neighbors that they were choosing to not enforce the law because it is a property developer and not a private homeowner.
In my experience, this type of unofficially permitted tree killing by builders is much more common and a far bigger problem than the rare issue of a private homeowner taking down a tree or two. Apart from the attitude towards new development, it is also an issue of corruption since the organizations representing builders are very involved (financially and otherwise) in local politics.