Nothing stops it. But consider whether your examples are actually helpful or practical.
Firearms have evolved to a stage where the firing mechanisms are highly reliable. The mechanical problems with a gun are not about how to make it go bang - they're all about reloading or (for rapid-fire weapons) barrel overheating. Magic might help to cool the barrel, but it won't solve problems with badly-designed mechanisms (like the infamous SA-80).
Similarly with a car engine. Spark timing on an engine is rather important, and at 6000RPM that's 50 sparks per second on a 4-stroke engine. A human being simply cannot do it fast enough or accurately enough.
Now guiding a bomb to a target - that certainly would be a good application of telekinesis. Telekinesis could also be useful for remote manipulation where getting people or even robots in place is impractical - think blast furnaces or nuclear facilities, for example. Lateral thinking with those kind of skills is a weak point in many works of fantasy. In Star Wars, for example, why do the Jedi not have lightsaber throwing knives? This is one of the hallmarks of modern fantasy - the impact of the magic system is usually analysed properly, not just for fighting but also for its impact on economics, working practises and everyday life.
Charles Stross has two running series of books where magic is systematised and studied scientifically. The Merchant Princes series, starts with the premise that travel between alternative worlds is possible (initially by skilled humans, but eventually reproduced technologically) and expands the scope of this to how it affects economics, societal development and warfare. The Laundry Files has more traditional magic, but with the premise that this magic is the result of algorithms which can be run equally well on electronics as on human grey matter.
For another fantasy example, Scott Lynch's Gentlemen Bastards series is set in a loosely Renaissance-based context, but one in which alchemy works. In medicine, plant breeding, poisons and various other areas, this world does not draw a line between what is alchemy and what is not, because in this world it is all "natural". (Yes, there is also more traditional magic, but the magicians have mostly hidden themselves away, and they don't publicise the extents of their power.)