Yup Obama was way better at getting illegal aliens out of the country than Trump was. The illegal immigrant population decreased by nearly 1,000,000 under Obama's two terms. It only decreased by 100,000 under Trump.

Surely that’s more to do with Obama’s clemency policies (DACA, sanctuary cities, etc.) than with “getting undocumented immigrants out.”

I guess when it comes to getting local democratic jurisdictions to cooperate with your law enforcement efforts, it helps to be a Democrat yourself.

Not all border adjacent local government, and especially law enforcement, is Democrat. As communities that directly interact with immigrants on a daily basis, I’m sure they were sceptical of Trump’s nativist view of immigrants (“not exactly sending their best, rapists and murderers” etc.) rather than it simply being bureaucratic friction.