Long story short, this is not in all cases. In other cases, which the enemies of Islam don’t like to bring up, a woman’s witness is sufficient, while the man’s witness is not accepted at all. In other cases, a woman’s testimony is exactly the same as a man’s. In fact, in the most important cases, where the actual transmission of narrations of Hadiths is either being classified as authentic or not, a woman’s testimony is exactly the same as a man’s. However, in cases where one man’s testimony is equal to two women’s testimony, it has to do with the situation itself and how men would be better at recalling something in that situation. Numerous scientific studies have even shown and made it very clear that when it comes to abilities such as spatial awareness and spatial abilities in general, men are significantly better at its performance than women. And this is perfectly fine! Men are better than women in somethings and women are better than men in other things, and this is not a form of injustice at all.
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.