That a party controlling both chambers of Congress and the Chief Executive Office (presidency) means they can pass whatever bills they like is a misconception, especially on the federal level, mainly due to two reasons.

1. internal disagreements within the majority party (the smaller your majorities in Congress are, the more problematic this becomes)

2. Senate filibuster (a procedural hurdle which requires 60 instead of 51 votes to end debate on any legislative business)

And currently, Democrats have a razor-thin majority in the House and Senate while Republicans can block any bills from even being considered in the Senate by filibustering.