There are only a number of jungle champs that can solo dragon early and even then it is an enormous risk because the jungle can end up dying to the enemy jg who then proceeds to finish dragon themselves. So, if the jungle does not take dragon while mid and/or bot is occupied with the enemy then they are either clearing camps or analyzing the map to determine which enemy is the most vulnerable to a gank.
When most or all camps are cleared, the jg will most likely have to B in order to restore health lost to monsters before they can even consider assisting a lane.
A jg cannot always gank a pushed lane given several factors including, but not limited to, wards, ally health and resources, and their own current level as opposed to the enemy’s combined levels. No matter which way Riot slices the jg cake, jg will usually have a difficult time staying on level with allies and enemies alike.
Dragon control usually goes to whichever team secures the most kills early. When forced into a defensive position, the jg will often be forced to roam to prevent continued feeding from allies. Farming becomes a secondary objective and sometimes impossible. Taking dragon will then require a team effort and the jg will have to face the harsh reality that one or more of their allies cannot make it in time to the dragon; so, the judgment call has to be made “better let the enemy have dragon then dragon plus 2 or 3 kills”.
Vision is always imperative when taking dragon and the jg usually does not pack a lot of wards for the job, often relying on the support to keep a ward on or behind it to alert when the enemy is going for it. But many “supports” absolutely refuse to purchase vision and then proceed to blame everyone else for the number of deaths that have occurred in or near their lane (that is a subject for another discussion).
When things really hit the fan and your team does win a fight for the dragon, champions may not be healthy enough to secure it and are forced to B. By the time the team is reassembled, the enemy is alive and ready for a rematch. When the jg and/or allies do manage to secure dragon with enemy champions nearby, half the time allies refuse to back off and proceed to die to healthy enemies OR the enemy manages to close the distance before anyone can retreat at all.
Exactly what is your main position that makes you so sore toward junglers?
Are you top? Then perhaps you should have brought teleport so as to port onto a ward when the team needs help in taking dragon.
Are you mid? Part of your job is roaming. Instead of whining about how the jg isn’t doing their job, make sure you’re doing yours.
Are you bot lane? Chances are that the jg is going to need protection from you against invasion as much as you need protection against ganks. Keep your side of the map warded and a good jg will help you as much as you help them.