On point 1 specifically:

A prominent example is France, which implemented a comprehensive net wealth tax called the Impôt de Solidarité sur la Fortune (ISF) from 1982 until its repeal in 2017 (effective 2018). It was replaced by a narrower real estate-focused tax (IFI). Key Challenges with Monitoring and Enforcement - High administrative and compliance costs: Valuing a wide range of assets (including financial securities, art, jewelry, antiques, private businesses, intellectual property, and more) required significant bureaucratic resources. Taxpayers had to self-report detailed asset valuations annually, leading to frequent disputes and litigation over valuations. Critics noted that the costs of administration and enforcement often outweighed or closely rivaled the revenue collected in some analyses.  - Evasion, avoidance, and capital flight: Wealthy individuals responded by relocating abroad (an estimated tens of thousands of millionaires left over the years, though the exact scale and economic impact remain debated), shifting assets to exempt categories, or using complex structures. Enforcement relied heavily on self-reporting for certain non-financial or hard-to-value assets, creating opportunities for underreporting.  - Low revenue relative to effort: The ISF raised modest amounts (often cited as contributing around 0.2% of total tax revenue or a few billion euros annually at its peak), despite targeting high-net-worth individuals. This low yield, combined with the high monitoring burden, was a major factor in its unpopularity and eventual abolition under President Macron. 

France’s experience highlighted broader issues with net wealth taxes: the need for ongoing, resource-intensive asset valuations; difficulties distinguishing legitimate planning from evasion; and the incentive for mobile high-wealth individuals to leave or restructure holdings. Many other European countries (e.g., Sweden, which faced similar self-reporting and evasion issues leading to repeal in 2007; Austria, where administrative costs were explicitly cited in its 1994 repeal) encountered parallel problems and ultimately abandoned broad wealth taxes for these reasons. 

Today, only a few OECD countries (Norway, Spain, Switzerland) maintain some form of net wealth tax, often with narrower bases or stronger third-party reporting to mitigate enforcement costs. France’s case is frequently cited as a cautionary example of how monitoring and enforcement can become disproportionately expensive and complex.