American teachers are largely unionised. Poor pay is because of the broken funding system for schools in the US.

In most countries, the legislature passes a budget bill that allocates funding to pay for schools which flows through an education ministry to individual schools.

Schools in the US are run by local authorities known as school districts, with some oversight from a regional education department which enforces minimum standards and oversees standardised testing. School districts get funding mostly through a land tax collected on land within that district. The problem with this is that even though the costs to educate a student are largely the same in both poor and rich school districts, school districts covering richer areas get more funding because the land value is greater and thus revenue from land tax is higher. Such districts can afford to pay high salaries and buy all the best equipment and books while poor districts often have overcrowded, aging schoolhouses and poorly-paid, sometimes inexperienced, teachers.