Protests take time to work. If you think that one day of protest is going to change it all, look to other movements. You can succeeded; it just takes much longer than people think they take. They want you thinking it's hopeless so when you don't get immediate results, they're happy to call them failures
Estimates are far higher than 100,000 people. Not just a small number. It was ~4 million on April 19th and ~3-5 million on April 5th depending on the estimates you look at
They are claiming it's "thousands" across the limited US media coverage, but you can find photos online of those kinds of numbers in various smaller cities alone
Protests too can be disruptive. They don't have to be just people along the side of the road, building, etc. For instance, here's thousands of people blocking a freeway in downtown LA as part of anti-ICE protests in February
https://abc7ny.com/post/la-protest-thousands-anti-ice-protesters-block-101-freeway-streets-downtown-los-angeles/15858620/
(Did get more media coverage indeed due to being more disruptive)
Organizing a general strike is also more difficult in the US with union membership being so comparatively low. Greece and the UK both have around double the unionization rate (~20% vs ~10%). Not impossible, and would be great to see, but protests themselves are a tool that can help get there. Help people see that people within your community are just a pissed as you are and you'll have a lot more people willing to join in. Unions are some of the people organizing various protests too. They are able to drive membership up because of it