"YES! Fine the companies that the spam is advertising for! "
That's exactly what the USA did in the Telephone Comsumer Protection Act of 1994 - except they made it trivial for the _victims_ to sue the spammer and advertiser in small claims court. (Joint and several liability)
The resulting liabilities put a large dent in unwanted phone marketing.
The statutory damages aren't large - only $500 per call, tripled for wilful breaches such as calling TPS-registsred numbers or withholding callerID, etc. But they don't need to be. If you're a business, imagine the impact of having to attend 20-50 small claims court hearings for this. Then imagine the "wee chat" your liability insurer is going to have about renewing your policy and next year's premiums - even if they decline to pay out because what was done was explicitly illegal activity.