4 Scenarios for 4 different levels of controll:
- Rough Controll (Half-meter acuracy and less):
The Elementalists are Competing with classical equipment (water pumps, flame throwers, excavators). They'd probably only outperform technology in areas where little to no standartisation is possible (agriculture in extreme terrain, disaster controll...).
- Fine-Controll (Centimeter Range): Hiring an Elementalist can possible become a valid alternative to buying machinery. Elementalist strive in situations where specialized machinery is too expensive, compared to buying the same labour as a service.
- Very Fine Controll (Below-Millimeter Range): Interesting jobs open up to Elementalists. Elementalist still strive in situations where technical equipment would need to be very specialised. Possible applications of water, and firebending become interesting for medical fields. Earth-bending becomes interesting for Technological applications.
- Ludicrous Controll (Really, really, really accurate): Elementalists dominate the material sciences. Cooperating earth and fire benders create new meta-materials at astounding rates. Water benders create the first working fusion reactor by bending water into deuterium. By manipulating surgical instruments made from volcanic glass, earth benders perform internal surgery.
Bonus Scenario: The Collective of Air-Elementalists announces, that it's cooperative effort to "bend" an Atmosphere onto the moon and keep it there, by working in shifts, have been an success. Moon colonization is expected to start beginning next Autumn.
Conclusion: Elementalists are horribly outperformed, when trying to replace existing technology. They only become valuable when working in jobs, that would otherwise not be possible. Considering that they have what amounts to telecinesis, that shouldn't be that hard to find.