I would like you to read the following research regarding the Hamas tunnel industry. It is quite long and very informative. I would like to point out that this was published by an unbiased Arab institute. I would also like to quote a specific part:
A similarly cavalier approach to child labor and tunnel fatalities damaged the movement’s standing with human-rights groups, despite government assurances dating back to 2008 that it was considering curbs. During a police patrol that the author was permitted to accompany in December 2011, nothing was done to impede the use of children in the tunnels, where, much as in Victorian coal mines, they are prized for their nimble bodies. At least 160 children have been killed in the tunnels, according to Hamas officials. Safety controls on imports appear similarly lax, although the TAC insists that a sixteen-man contingent carries out sporadic spot-checks.
All told, the tunnels have been a mixed bag for Hamas. While its detractors praise—albeit begrudgingly—its success in reducing the impact of Israel’s stranglehold, perceptions of corruption inside the organization have intensified. During the renewed fuel shortages of spring 2012, there were widespread allegations that Hamas leaders received uninterrupted electricity and that gasoline stations continued to operate for the exclusive use of Hamas members. True or not, they fed a growing mood of recrimination that Hamas had profited from the siege.