Serving as a cop in America is harder than ever — and it comes down to respect. A deficit of respect for the men and women in blue who daily put their lives on the line for the rest of us is hurting recruitment and retention and placing communities at risk. This month, Sgt. Christopher Brewster of the Houston Police Department was shot and killed while responding to a domestic-violence call. Several hours later that same day, Officer Stephen Carr of Arkansas’ Fayetteville Police Department was ambushed and executed while sitting in his patrol vehicle. Last week, Det. Joseph Seals...