In fact, there is a switch for the glove box light. It's buried behind the fascia and requires an awful lot of major disassembly to access it. I had/have the same problem with my 2013 Roomster. This is a normally-closed switch which, when everything is as it should be, turns off when the glovebox lid is closed. However, on my car this switch has twice become detached from its mount so that means it turns on permanently. This is a real safety hazard which I reported to Skoda but they were very evasive and I never got any joy from them. The switch seems to be held in place by clips and can be dislodged if the car receives a sudden jolt, such as hitting a pothole. It should be retained far more securely so this cannot happen.
What is the big issue, you might wonder? I only became aware of the problem when I went to the car one day (after it hadn't been used for several days) and there was a strong smell of burning. Then I noticed smoke coming from the storage compartment above the glove box. We always keep a bundle of tissues in there and when I pulled them out the bottom of the pile was severely scorched. Another half hour or so and they would have been in flames. The bottom of this upper storage compartment had melted right through and the glove box lamp was glowing through the hole. It was only then that checks revealed the glove box light switch wasn't working.
The first time this happened I took it to the Skoda dealer and it took them nearly all day to fix it. The mechanic was not well pleased when I went to collect the car. Said it was a "right f'in b'std" of a job. A month later the same thing happened. They refused to repair it and just took the bulb out.