Did segregation exist during slavery? And does that mean slaves were better off?

No. This is an important distinction.

The fact that segregation became especially prominent as a post-emancipation legal and institutional system does not mean that enslaved people were better off under slavery.

Why?

Because slavery itself involved a much more fundamental form of domination.

Under slavery:

people were legally enslaved and treated as property.

After emancipation:

slavery was abolished, but racial hierarchy could be reconstructed through different institutions and practices.

So think of it as:

Under slavery

racial hierarchy + slavery

After emancipation

slavery removed + racial hierarchy persists/reconstructed through other mechanisms

Those mechanisms could include:

• segregation;
• disenfranchisement;
• racial violence;
• discriminatory labor arrangements;
• exclusion from institutions.

Therefore, the disappearance of slavery did not mean the disappearance of racial hierarchy.

And the emergence of segregation after emancipation does not imply that slavery had been a more favorable condition.

It means the form of racial domination changed.