This isn’t quite right. Trump didn’t really modify laws. That isn’t even something he can claim to do since he is the head of the Executive branch, not the Legislative one. He issued executive orders, many of which were illegal, and he had some cronies who enacted some of them anyway - others did not enact some of these. He did rescind many policies, but he can’t just make laws go away on his own. There are literally hundreds of court cases currently challenging these executive orders - seeing as how the judiciary is the primary check on the executive branch, that is the system working to check presidential power.

However, I am not a liberal, I am a socialist and do not think this is working well - there are many problems here. The highest levels of the judiciary have been largely captured by far-right judges, many of whom are specifically aligned with Trump’s goals and support the unitary executive theory. Also, this method of checking presidential power is extremely slow. For every illegal action Trump’s administration takes, a court case has to be crafted, filed, heard, and adjudicated. Every one. And invariably, some will not reach the correct outcome and others will never actually be taken to court - there are just too many.

Basically, the administration is using the fact that they control every branch of government to dismantle or capture core government agencies and to provide cover for various illegal actions - forcing them through if only temporarily for various political and structural ends. A soft coup, basically. So yeah, the fact that something like this is possible is proof of the flaws inherent in this system of government.