Not that taking some ideas from Europe is a good or bad thing... but I would be hesitant to emulate Europe's approach to tech.

The difference in salaries for high-skilled labor has been diverging for decades and in a lot of cases result in 2x-3x less than you could get in North America.

Even that depends. The one's in Switzerland are absolutely useless and are just used by the core members to make it impossible to fire them. I must pay the union, can not opt-out and they waste my money since a decade. Ours has an unemployment insurance which didn't pay for half a year instead of a few weeks. When I once needed their help, nobody answered. This despite them being available across our whole organization. None out of many helped. I am looking at you Complan, you are the worst. /r

European labor unions generally have industrial density now because many European countries' labor laws encourage bargaining at the sectoral level. U.S. labor law is not sectoral in orientation.

Be careful not to confuse cause and effect. Labor and social democratic parties were able to pass sectoral bargaining laws because unions had already achieved organizing density in strategic sectors, and business interests preferred to channel unrest into the courts and labor boards.