People sometimes simply forget that they are supposed to leash. Just remind them. Every once in awhile you'll get an oddball that will rage at you, or on occasion (this is much more common) you'll get someone who just ignores what you're saying (they're afk, foreign, or just don't give a damn) and doesn't come or communicate or anything. Usually, though, people will scout the river bushes for invades and throw in an auto-attack.
The best leash is a dual leash - having the mid-lane "leash" the golem, and having the other lane (depending on your team color this is either bot or top lane) "hard leash" it after (essentially they beat it down to 1/2 health and then gtfo). This allows you to clear the jungle insanely fast, and allows you to gank early on two levels - one because your clear is faster, and two because your health is higher. They might miss a minion or two, but the early gank makes it well worth it. Do this for your jungler and they will love you.
Sometimes the hard leash is not the best option though, for instance if they are hard-countered in their lane, they need to reach level 2, 3 & 4 as fast as possible, and missing out on that early xp really cripples them.