I’d be interested in knowing if the OP could name a single person on the left who isn’t upset about the murder of 2 police officers.
As a political issue, your real question, rather than the one you asked, is “why doesn’t this incident drive all people to want a Southern border wall to prevent this from ever happening again”.
If you asked a more respectful and straightforward question, you could have promoted a productive dialogue rather than a question designed to accuse and denigrate. Who knows, you may have gotten an answer like this: It’s pretty clear that just about all people (left and right) are supportive of increased border security that includes components of srrategic border barrier, and increased human and tech surveillance, along with comprehensive immigration reform. It’s the focus on an unspecified “wall” rather than working on the specifics of border security that has been the problem — sadly, both political parties have joined in this divisive dance to the detriment of progress.
Snipes, even when hurled between the lines, aren’t very helpful.