No, any weed can be cooked, even stubborn weeds. Thermal weed control works the same way on all plants. This is in contrast to chemical weed control methods, where there is increasing evidence that plants become resistant to the active substance (frequently glyphosate).
Even stubborn weeds with a strong root structure, such as dandelions, horsetail, etc are effectively controlled with the WAVE method. For these, several treatments will probably be necessary, as the root structure has built up reserves and reaches deeper into the ground. At every treatment with the hot water of the WAVE machine, the root structure becomes more exhausted until the weed no longer returns.