Air carrier flight crew reported a ground conflict with a ramp vehicle during taxi into gate.

Narrative

Ramp Tower cleared us to enter the ramp at spot XX and then to proceed (after a brief stop at XX) to gate XZ. As we were nearing the 'throat' of that point where the three entry lines converge into one; abeam gate XY I suddenly noticed a tug driver pulling into our taxi path. There wasn't much time or room and in the dim light I had to make an instantaneous decision to panic stop the jet. The tug also stopped and after some hesitation (probably to count his blessings) he pulled a U-turn and left towards the terminal. Over the radio we notified ramp tower of the incursion and near miss; to which they asked if we could make out the tug number. We couldn't. It was a wet; dark night.Too many near misses with tugs in recent months. Maybe not as close as this one was; but certainly too many. I see aggressive and rushed drivers and the distance and respect that they show towards our airplanes has diminished every year. I'm sure that driver will look twice; for a while. Then it's back to the races. I'm worried about this trend.You have to enforce; not just have rules. If they are driving the way they do it's because it's condoned by those looking the other way. I'm sure it's not so simple; but if you put a cop in there every day but at different times for a week; two weeks or a month the word will get around. Hate to say it; but the reality (we all know) is that unenforced rules lead us all to ignore them.