> much easier for Obama to do it because there were not throngs of protesters trying to stop his ICE officers

Yes there were [1][2]. New York City Council members were arrested [3].

Obama's ICE was simply more focussed on detaining and deterring illegal immigrants because immigration was a political liability for him. For Trump, efficiacy isn't as important as messaging.

[1] https://www.voanews.com/a/barack-obama-immigration-raids-pro...

[2] https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3793700

[3] https://www.nbcnewyork.com/news/local/protest-arrests/211895...

Assumed political liability.

At the time, sure. With the benefit of hindsight, one of Democrats’ strategic fuckups over the last decade was forgetting that it is one.

What's the cause and what's the effect? Less protests because ICE under Obama wasn't taking such a heavy handed and legally gray approach perhaps?

Great question! It was pretty clear that people would be protesting Trump from the day he was re-elected. His methods undoubtedly haven't helped, but I'm pretty sure there would have been protesters regardless.

I don't have the links handy, but ISTR that both Obama and Biden counted turning folks away at the border as equivalent to a deportation. That juices the deportation metrics without being nearly so disruptive.