Long story short, this is not in all cases. In some cases, women get more than men. But in other cases, where there is a son and a daughter, the son would definitely get more. If one tries to think about the wisdom that may be behind this, one will realize that the male in Islam is the one that has the financial burden upon his shoulders; in other words, a male has more economic responsibilities than women in Islam, including it being obligatory on him to provide for his wife and children. Therefore, since the man has more economic responsibilities than the woman, in certain cases, it would make perfect sense that he gets more inheritance money than the women.
To conclude, it should be noted that in Pre-Islamic Arabia, they used to bury their daughters alive, as having a daughter was seen as a disgrace. Women were treated as property with no rights at all. Even in the western world, women were deprived of many of their rights until recently, such as voting. Islam liberated the women, gave them honor, dignity, and their due rights. This is why, despite all of these outrageous, ongoing allegations against the way Islam treats women, most people who convert to Islam are in fact women!
And Allah knows best.