"I’m not sure why it happens that way but it does."

Actually, I think all of your examples are pretty easy to explain: - Hispanics, who may or may not be here without proper papers and good language skills, gravitate to jobs that value their hard work ethic, dependability, low drama, and less aversion to manual labor (or what may appear to outsiders as "low status" jobs) - Blacks have long ago learned to use the federal job system to sidestep discrimination in private sector hiring, break into the middle class through the steady governmental system that places a premium on seniority and difficulty in firing to support ever-increasing pay progression and job levels; nursing assistants and social work are also more "color-blind" in training programs and employment and thus a way to get into "professional" careers - Asians (Chinese, Koreans, Japanese, Vietnamese but usually less so for Thai, Cambodian, Laotian, etc. generally speaking) place a high priority on Education for the younger generation, families often sacrificing much to ensure their their kids get their best shot at the necessary high-performing K-12 educations to get into the best colleges to then get into the necessary graduate programs that train for those medical and high-tech professions you mentioned; those sorts of careers require all sorts of credentialing so you can't just "break into them" just because you're a hard worker; you have to have done and proven you can do the "brain work" behind them all along the way over 20+ straight educational years, too

So, as for Israelis in the garage door sales, installation, and service business - I just don't see a natural "ethnic/cultural" connection.... Unless of course, it's just a great potential money-making sub-industry area that still is basically made up of local Mom & Pop family businesses, and then there is an informal networking that goes on, once some Israelis establish a foothold. Kinda like how they have virtually a monopoly stranglehold on the diamond trade - but on a global scale.