Different surveys shows that appr. 75-98% of college students in the USA have cheated at least once during their academic careers. I believe, it is caused by Internet accessibility and by the increasing number of opportunities to use other's person work online. That's why plagiarism checker as Turnitin or Unplag could help to detect plagiarism in the students' works and to prevent possible plagiarism in the future.
Yes, it is important for high schools and colleges to use services to prevent plagiarism, because cheating is very popular. Most students, even good students, admit that they have cheated sometimes in their school career. Cutting down on plagiarism prevents the good, honest students from being overlooked academically. Monitoring student conduct is fair to everyone.
With the wealth of information available online, and increasing pressure to do well in schools, some students have turned to copying the material of others to cut corners on their educational demands. I believe educational institutions should be able to use services such as Turnitin to check for blatant plagiarism in students' work. There is no way a teacher could be expected to check every online source for each student, but these services can do so in a fraction of the time, preventing students who are cheating from receiving passing grades for work that is not theirs.