I'll give you a non-legal opinion, having been the trustee of a number of family trusts for over twenty years, and having created a couple of trusts myself for my own family members.
I haven't and would not pay day-to-day living expenses (doctors visits, gas and mileage to college, etc), even if the trust was for that one specific person. The individual has to live within their own means. I do pay for college tuition, room and board if it is an away school, and for the books each semester.
The trust is written with trustee discretionary powers to pay other things if I deem warranted, but I don't believe living expenses are warranted, nor are they within the intent of the original donor looking for long term growth and protection of assets, and ultimately passing that money on to future generations.
The investments are targeted for fully invested portfolios looking for long term sustained growth, not a lot of money sitting around in cash positions available to be spent at will.
I'm sure others will have different opinions and operating standards, and that's fine. I just think you go down a slippery slope without any ability to 'draw the line' somewhere. If a trust pays for gas, then why not pay for insurance on the car, and tires, and inspection, and to get it fixed or replaced, etc, etc, etc.
So I don't believe your trustee is out of line at all.