They might have perfectly good reasons. I just cut down two massive trees that were in front of my house, and there were so many reasons to do it.
There are rarely "perfectly GOOD reasons" to cut down mature healthy trees. The reasons such as they are usually rooted (!) in selfishness and laziness with no real consideration of others and future generations. You cannot replace a 100 year old tree or even a 50 or 20 year old tree overnight.
A mature tree is usually a beautiful and attractive addition to a local environment anywhere but especially in a built up area. It adds so much in terms of wildlife support, shade, leaves and bark trap fine particulates, dust, and pollutants (such as nitrogen dioxide and ozone) from traffic emissions, absorbing and storing carbon dioxides, intercept heavy rainfall, slow down water run-off, and can reduce the risk of flash flooding by up to 99% including roots absorbing water. Replacing it with a small ornamental bush is not like for like in terms of visual amenity or overall benefit.
The individual benefits from healthy tree destruction (a lighter room, less shade in the garden, less leaf fall, space to build or develop) are 9/10 outweighed by the wider benefits to the community visually and environmental benefit.
If you don't like shade or are scared of a branch falling, don't buy houses with mature trees, buy a different house with an aggregate drive and fake grass and leave the trees for future generations.
Tree issues can be managed by tree surgeons and reducing the height or crown of the tree, thinning the canopy, root barriers and so on. Cutting down a mature healthy tree is not the only solution but society is now all about convenience.