they do make an automatic that isnt a converted gun you can convert them yes but they also make a glock 18 c that is single or automatic fire they stopped making them and are a rare gun which is also in the matrix the black guy has 2 of them i quote from the link below
Why on Earth did Gaston Glock design a fully-automatic pistol? This is one of the most asked Glock questions. Controlling such a beast is well nigh impossible except for the most well-trained operator, and any such gun clogs up so fast with carbon and debris that it's use would be limited to the most specialised needs. Glock themselves offer a training course specifically for the Glock 18, and at one point (not sure if they still do it) they wouldn't sell them to any customers in the US until they had taken the course.
In 1983 when Gaston Glock designed the original Glock 17, he envisaged that there would be a wider market than just the Austrian military, for whom the 17 was designed. Consequently, he designed the 17L for target shooters (basically a 17 with a longer slide) and the fully-automatic 18 to increase the appeal of the gun to the police and military markets. Little did Gaston know that a few years later paranoia about "plastic guns" in the US would increase demand for his polymer-framed pistol to unforseen levels, and provide the impetus for the slew of other Glock models that have subsequently been produced.
Sales of the Glock 18 appear to have gone mostly to SWAT teams and the like, although apparently the Italian airport police carry them.
Mr Glock cleverly designed the Glock 18 so that you could not easily take a Glock 17 and change a few parts to make an illegal fully-automatic firearm.