I think not. Money is not the only way to express appreciation. A tip is appropriate in some contexts, but not in others. The relationship I have with professionals is very different from that with a bartender, waiter, porter or driver. I tend to express appreciation to professionals by giving them more of our business, referring other clients, or with gifts which match their individual interests.
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And a CPA, Lawyer, etc. is usually compensated at the end of the fiscal year in the form of a bonus and if they are a shareholder a distribution. ANd bonus's are typically based on your performance, so yes people are indirectly tipping their CPAs and Lawyers but it is built into their billable hour rates.