Here's an example of a harassment statute from uslegal.com:
"A person is guilty of harassment in the first degree when he or she intentionally and repeatedly harasses another person by following such person in or about a public place or places or by engaging in a course of conduct or by repeatedly committing acts which places such person in reasonable fear of physical injury."
Note how words and phrases such as "repeatedly" and "fear of physical injury" appear. This is common to prove harassment and does not apply to WBC. Unfortunately there isn't always a legal remedy to a problem, such as funeral picketing, though this law puts restrictions on funeral protests and was recently upheld. I disagree with the Court's assessment but we shall see what the Supreme Court says if they hear the case.
That only applies to first degree harassment.
Besides, WBC's protests are repetitive, though they aren't over many days. They track down specific people and say the same thing for hours. Even if you don't consider it persistent, it's still harmful and disruptive.
"S 240.26 Harassment in the second degree.
A person is guilty of harassment in the second degree when, with intent to harass, annoy or alarm another person:
He or she strikes, shoves, kicks or otherwise subjects such other person to physical contact, or attempts or threatens to do the same; or He or she follows a person in or about a public place or places; or
He or she engages in a course of conduct or repeatedly commits acts which alarm or seriously annoy such other person and which serve no legitimate purpose.
Subdivisions two and three of this section shall not apply to activities regulated by the national labor relations act, as amended, the railway labor act, as amended, or the federal employment labor management act, as amended.
Harassment in the second degree is a violation.
S 240.30 Aggravated harassment in the second degree.
A person is guilty of aggravated harassment in the second degree when, with intent to harass, annoy, threaten or alarm another person, he or she:
Either (a) communicates with a person, anonymously or otherwise, by telephone, or by telegraph, mail or any other form of written communication, in a manner likely to cause annoyance or alarm; or (b) causes a communication to be initiated by mechanical or electronic means or otherwise with a person, anonymously or otherwise, by telephone, or by telegraph, mail or any other form of written communication, in a manner likely to cause annoyance or alarm; or
Makes a telephone call, whether or not a conversation ensues, with no purpose of legitimate communication; or
Strikes, shoves, kicks, or otherwise subjects another person to physical contact, or attempts or threatens to do the same because of a belief or perception regarding such person`s race, color, national origin, ancestry, gender, religion, religious practice, age, disability or sexual orientation, regardless of whether the belief or perception is correct; or
Commits the crime of harassment in the first degree and has previously been convicted of the crime of harassment in the first degree as defined by section 240.25 of this article within the preceding ten years.
Aggravated harassment in the second degree is a class A misdemeanor."