I sometimes see this type of misuse of “of”.

Problem:
The preposition “of” is the wrong word for this sentence.

Explanation:
Unfortunately, many use the preposition “of” when they should use the auxiliary verb “have” or its contracted form. As an auxiliary verb, “have” is used with past participles to form perfect tenses. For example, “I went to the store.” can be rewritten as “I have gone to the store.” or “I had gone to the store.” Another example: “They were the nicest neighbors.” can be rewritten as “They have been the nicest neighbors.” or “They had been the nicest neighbors.”

I believe that the use of “of” instead of “have” when the latter is appropriate represents

• a laziness that favors contractions,
• poor pronunciation and listening skills, and
• ignorance about the basics of English.

The contraction “could’ve” is easier than the word sequence “could have” to say. This supports my “Devolution toward Simpler” hypothesis. Combine this laziness, poor pronunciation and listening skills, and ignorance about the basics of English, and you get “She could of called.” — ouch!

Solutions:
“She could’ve called.” or “She could have called.”