The stupid "safety nozzles" which the EPA allows to be sold in this country have the spring loaded black tips which automatically shut off once the tank is filled. The catch is that after about the second or third use the plastic and spring parts begin to wear out and the nozzle starts leaking so you need to replace it.
Or you could just swing up to Canada and buy the solid yellow gravity flow tips which can be used a lot longer.
But still not as long as the flexible metal spouts which your Dad or Grandfather was able to buy. If you want one of those, you'll have to check out a farm auction or estate sale and hope you can afford to bid high enough.
I'm not sure what you have on your two gallon can. It could be that since they are only about 40% of the weight of standard five gallon can so the parts on the "safety tip" don't wear out as quickly or that such small cans are exempt from the EPA rules on pure gravity flow nozzles.
The point is that the EPA, in trying to protect us from a few morons who try to pour five gallons of gas in a tank that has space for only three, they've created an even bigger hazard with their mandated safety nozzle design which will start failing long before the straight gravity flow spout.
Thanks to both of you for your replies. I understand now, and why am I not surprised. I remember when the government tried to keep toddlers from drowning in 5 gallon buckets. They were trying to mandate leaky buckets so that water couldn’t accumulate and drown the unlucky children. Fortunately they apparently figured out that a leaky bucket is no bucket at all. At least I hope they figured it out.