A free rider is someone who can increase consumption of a service without incurring additional cost.

My proposal aims to link consumption and cost as closely as possible, minimizing free riders. I think any alternative would increase free riders.

Consider vehicle registration. It's typically not a flat rate per vehicle. Antique vehicles and motorcycles get a discount. Heavier vehicles and commercial vehicles pay more. These crude adjustments make the registration fee more closely match the usage cost the drivers will impose on the roads. A gas tax is a closer but still approximate measure of road usage. A general tax is completely disconnected. Why should a New York City resident without a car subsidize Alaskan highways?

No system will be perfect. A kid on the back seat is literally a free rider (unless a toll operator charges for passengers). But the weight of an extra kid does not add much wear and tear to a highway. I think that the incentives work out best when those who have a stake in the operation make the decisions, rather than distant planners making inflexible one-size-fits-all rules for others.

I believe the price of a t-shirt does include the full cost of shipping (how else would the container ship lease get paid?). If the t-shirt factory worker pays for housing or health care with their salary, then the price of the t-shirt also includes these costs.

Of course public subsidies can work to the benefit of corporations at the expense of taxpayers; do I need to say it?