Why might there have been a stronger anti slavery movement in Britain than in the United States in the 1790s?

Industrial revolution and The influence of the Quakers

Explanation:

industrial revolution was originated in Britain. As the economy started to transitioned into using machines more efficiently, the need to use slaves became non-existed. This strengthened Britain's anti-slavery movement in 1790s

Beside that, there's the quakers. The Quakers were a popular religious groups that held a more progressive views compared to most churches that exist at that time. They believed that God exist in every individuals and every followers of God should receive equal treatments.

They gained popularity in mid 17th century, and became large enough to acquire the number of followers that can pressure the parliaments to make the use of slavery became illegal.

your answer is

to dominate europe

and i know for a fact it can't be the others