If I was the instructor...
I would first strike out all wordiness: e.g. in the current period; at a moment; or... at the present time etc. There are numerous "wordy" lists available on the Internet that you can refer to for this part.
Then, to detect hard to prove plagiarism, I would search only on significant or weighty phrases and ignore the adjective fluff--except for superlatives and qualifiers (few, most, many--which many students/people have trouble changing into different words).
Focus on phrases that wouldn't seem to matter to a student who is copying, rather than comprehending/understanding what he/she reads... like "most people", "few people", "many Americans", "few Blacks", etc. Also focus on the "meat"--phrases that students would strive to retain because it sounds more sophisticated or more academic.
So from the student example, I would pull out phrases like these, adding plus signs between them:
U.S. racial+urbanized+occupationally heterogeneous+anti discrimination+most white Americans+blacks'+status [blacks' as plural possessive]
Put only that string of select words and phrases into Google.
The second Google hit shows enough resemblance--all the words are present. That hit goes to Google Books:
Racial Attitudes in the 1990s: Continuity and Change, pg. 18
edited by Steven A. Tuch, Jack K. Martin
In other words, don't take a student's full sentence to use when checking Google. Instead, pull out phrases that sound like the student is a professor-wannabe, words the student would rarely or very rarely string together based on the student's age, college level, past writing assignments, past academic performance, speaking habits, etc. For example, if a 19 yr old with a C-average turned in that mess, I'd immediately think "plagiarized!"
For in class teaching strategies, professors might assign speaking presentations early in the course. As each student presents orally, write on an index card the student's style and speaking level. e.g. Notes like: uses simple words; no sophistication; uses few/too many adjectives; uses good analogies; noun/pronoun-verb conflicts like "He run" instead of "He ran". The cards will be a reference for you when evaluating writing assignments throughout the course.
A second teaching strategy: Print out a paragraph from a textbook, say 5 sentences long, with a copy for each student. Make it 'count'--assign grades for this exercise. Have them silently read it. Instructions:
Turn the paper over and don't look at it again. In 3 to 4 sentences (reduced from 5) write "in your own words" what the author said. You may not use any significant phrases or adjectives from the original text except identifiers like age, gender, nationality, etc. (Men; women; middle-aged; American; Canadian, etc.) You may not simply replace words in the original with synonyms. [Alternate assignment: Same instructions but they may refer to the original and give permission to reuse only 3 significant words or phrases from the original version. If more than 3 are used, it will result in an F for the exercise.]
Teaching strategy #3: Review good class note-taking. Specifically instruct the students to take notes for this class. Teach for 15-20 minutes. Stop and pick several students to refer to their notes and re-tell the class the main points you made but they must put the ideas into complete sentences. Their version must re-tell what you taught, as closely as possible. After several students share their retelling, review with the class how "important pieces" in lecture notetaking is similar to the task of "paraphrasing" points from texts. Talk about how hearing significant pieces from your lecture for notetaking purposes uses the same skills they need to also 'hear' /listen for significant words/phrases in texts. Discuss why they must use "phrase quotes" on significant pieces when paraphrasing for a writing assignment, in addition to sentence quotes. And discuss attribution for both.
I enjoyed writing this and hope it sparks further ideas.