let me clue ya in :P:
first off, we don't get paid anything--not really--my highest paying 2-week check was $21.34 (which would be great if this was the early 1900s)... we make our money off our tables, almost like renting out a booth in a barber shop except if we make more than minimum wage off of tips alone, they don't have to pay us (if we make less and they do have to pay us, and this continues to happen, they boot you--that's if you're really costing them. if you're making $6.53 then they just pay the difference...). then, they take the money we're making (3% of out total sales) and split it among the hosts, bussers, and bartenders (in an effort to not pay them)--that's 3% coming off the meal you're not tipping on. so, if you meal was $100, we now just payed $3 to wait on you, depriving us of a table that would actually tip.
as far as cash tips... that really is thoughtful, but out of an attempt to stifle potential audits, and the company not making the upmost amount of money off you... since they're taking 3% of your cash sales (in an effort to combat any "hiding" that is going on on cash tips), it really evens out in the end... still though, it always makes me smile when someone tries to do something nice.
but back on subject... uh, ISTJ's, right... uh:
i've noticed something with Pi-dom.'s, that their experience (regardless of which, and yes, Ni does also work off of experience, it treats it differently and works through a different medium) is their reality. so, not to poke fun at ISTJ's, but my brother-in-law and my close (amazing) friend are both ISTJ's and are terrible tippers. but, back to the "experience" factor, some that i work with will tip outrageously (like 50%). when i raise my eyebrows at them, they're just like, "hey, i've waited (or am waiting) tables. i know how it is, plus that person is sweating enough to fill my drink without a pitcher". in other words... i think experience plays a large role for everyone, but maybe doubly so for Pi-doms??? eh...